Parasitic wasps lay their eggs directly into the eggs

[lina_cheung]

Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

Which of the following conclusions can properly be drawn from the information above?

(A) The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.
(B) Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.
(C) Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.
(D) Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.
(E) Parasitic wasps use visual clues to calculate the size of a host egg.

Answer is A. Can somebody explain it? Thank you

[rfernandez]

Generally speaking, we want the answer choice that can be logically deduced from the premises. Anything that strays away from the text will be a wrong answer.

A) The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.
(B) Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.
(C) Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.
(D) Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.
(E) Parasitic wasps use visual clues to calculate the size of a host egg.

B - Out of scope. We have been given no information about the available defenses that the host insects bring to the table.
C - All we know is that the wasps always lay exactly the right number of eggs. We have no information to determine whether the wasps learn this behavior or if it's something else (such as instinct).
D - No information about the speed of death for overpopulated vs. underpopulated host insect eggs.
E - No information about visual cues vs. any other cues.

A follows directly from the argument (even if it doesn't really say anything of much importance). If you want to know the size of the smallest possible host egg, you could study these wasps' egg-laying behavior and make some calculations based on the data you collect. Sounds plausible.

[sandeep.19+man]

I am stunned. The "smallest host egg" is never mentioned in the CR. How can the conclusion be related to that.

Can the tutors explain this without using POE?

Thanks

[RonPurewal]

I am stunned. The "smallest host egg" is never mentioned in the CR. How can the conclusion be related to that.

the passage includes information about "any suitable size of host egg"; therefore, the smallest such size is indeed within the scope of the argument.

Can the tutors explain this without using POE?

Thanks

by "this" do you mean why the above concept is ok, or do you mean that you actually want us to explain the answer to the problem?

if you want an explanation of the answer, here you go:
the passage states that "Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg".
therefore, we could observe the parasite's behavior until we saw a host egg for which "exactly the right number" was 1 egg.
since the wasp cannot lay less than 1 egg, this particular egg would then be the smallest possible host egg.
therefore, we should be able to determine the smallest possible host egg, so (a) is justified.

[hi]

The Ron,
you are amazing. Very nicely explained.

Thanks,
El Greco: X to x and x to X

[RonPurewal]

thanks
(this isn't the thread for the el greco problem, but that's ok in this case)

[rhitian]

I think choice D makes for a very strong contender if you view it from a slightly different angle... specifically the words "more quickly"

The argument states that "If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space." -> So we at least know that the larvae hatched.

"If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae." -> The Eggs never hatched.

So the developing larvae ( which can be used to describe larvae both developing in the egg or developing outside) will be lead to death "more quickly" if not enough eggs are laid.

Yes, Choice A is better and is the only correct answer and all others are therefore incorrect answers and I am reading too much into...I know I know..

[mirantdon]

LEGEND AHH.. WAIT FOR IT ..! ROOONNN.!

[RonPurewal]

rhitian --

"If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae." -> The Eggs never hatched.

1) i think you're confusing the host egg (which decays) with the actual wasp eggs inside it; in this choice, nothing is stated about the wasp eggs.

2) "larva" refers specifically to a juvenile stage of an animal that has already hatched from its egg. (you would of course not be expected to know information that is this specific.)

So the developing larvae ( which can be used to describe larvae both developing in the egg or developing outside) will be lead to death "more quickly" if not enough eggs are laid.

nope. in both cases they are larvae, hence post-hatching.

[chembeti_aravind]

I am stunned. The "smallest host egg" is never mentioned in the CR. How can the conclusion be related to that.

the passage includes information about "any suitable size of host egg"; therefore, the smallest such size is indeed within the scope of the argument.

Can the tutors explain this without using POE?

Thanks

by "this" do you mean why the above concept is ok, or do you mean that you actually want us to explain the answer to the problem?

if you want an explanation of the answer, here you go:
the passage states that "Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg".
therefore, we could observe the parasite's behavior until we saw a host egg for which "exactly the right number" was 1 egg.
since the wasp cannot lay less than 1 egg, this particular egg would then be the smallest possible host egg.
therefore, we should be able to determine the smallest possible host egg, so (a) is justified.

Wonderful logic. Thanks Ron.

[RonPurewal]

glad it helped

[YuL733]

this forum really helps me a lot in understanding the prep CR questions. So first of all i have to say thanks to you all.

as for this specific question, i'd like to put my two cents into the discussion.

i chose D coz i assumed competition worked slower than decay and now i realize this assumption is just unreasonable.

but still, i don't think choice a is logically perfect. As per the explanation above, we can only know "the size of the smallest host egg that a wasp could theoretically parasitize" must be no bigger than any host egg laid with one wasp egg, but it's really hard to know how small can be the smallest. if it has one wasp egg, it only means it cannot hold two eggs, but maybe 1.5? maybe 1.09?(and they all carry one parasitic egg) how can we be positively sure which is small enough to hold exactly "one" wasp egg? So...
Maybe i'm just overthinking too much.

well, i know this 2015 and the last post was in 2012 and there is little hope of any reply

[RonPurewal]

still, i don't think choice a is logically perfect.
...
Maybe i'm just overthinking too much.

if this kind of thought crosses your mind, you are almost certainly looking at the CORRECT answer.

on GMAT CR problems, the wrong answers are always COMPLETELY wrong, for fundamental reasons that are not subtle at all.
so, if only petty objections come to mind (as is the case here), then you're probably looking at the right answer.

if you have to start making up random figures with decimal places, then you're DEFINITELY looking at the right answer. (:

[RonPurewal]

also--
you can't simply object to an answer. if you want to argue that some answer choice is wrong, then you MUST ALSO argue that some OTHER choice is actually the correct choice!

it's pretty clear that, in making the objections above (decimal points and all), you're not thinking about the other choices. you're just looking at choice A and saying "meh, not perfect".

if you were to examine ALL the choices, you would find...
A: "meh, not quite perfect"
B: completely wrong
C: completely wrong
D: completely wrong
E: completely wrong.

if you want black, and the choices look like (a) dark gray, (b) white, (c) white, (d) white, and (e) white, then ... you know which one is right.

[RonPurewal]

well, i know this 2015 and the last post was in 2012 and there is little hope of any reply

???

if YOU post on april 19, 2015, then "the last post on the thread" is ... april 19, 2015.