One RC question needs clarification

[RonPurewal]

However, I choose A. Since the 1st sentence of the passage--More selective than most chemical pesticides in that they ordinarily destroy only unwanted species, biocontrol agents eat, infect, or parasitize targeted plant or animal pests.-- told me a difference between chemical pesticides and biocontrol agents.
Can instructors told me why A is wrong, please?

you must have rushed through the question, because, well, you've accidentally formulated a completely different question.

the actual question says...
According to the passage, which of the following is a concern that arises with biocontrol agents but not with chemical pesticides?

so...
you're not just looking for "a difference between" these two things (= the question you apparently formulated in your head). you need something that biocontrol agents DO (green thing), but that pesticides DO NOT do (red thing).

choice A describes something that, according to the first sentence, biocontrol agents generally DO NOT do, but that pesticides DO (since they're less "selective"). both of those are exactly the opposite of what you want.

read the questions slowly. take the time to understand them fully.

[RonPurewal]

oh, and, by the way,

The OA is E.

... no, it isn't. (no wonder you found this problem troublesome!)

[RonPurewal]

Furthermore, I have another question, which is more important.
I know that the last sentnce of the passage answers the above question. However, I didn't read the last sentence when I was dealing with this passage. I just skim very quickly after I read this sentence: "The paucity of known extinctions or disruptions resulting from indirect interactions may reflect not the infrequency of such mishaps but rather the failure to look for or to detect them“.

that's fine—but, when you see "Moreover" (which basically means "okay, i'm talking about something else now, guys"), you should stop skimming, and start reading again.

in other words, the "moreover" means you aren't talking about that ^^ anymore.

[RonPurewal]

Thus, I am confused. How can I read the whole passage very quickly and meanwhile notice some sentence like the last sentence in this passage? Thanks in advance.

"how can i read more quickly?" ...well, basically, you can't, nor would you want to (since, generally speaking, quick reading = careless reading).

the point is not to read fast. (i can't read fast at all; i'm dyslexic. the average poster on this forum probably reads faster than i do.) the point is to answer the questions efficiently.

here, you actually have two tasks, not just one:
• find a bad thing about biocontrol agents
• find a bad thing that's NOT an issue with pesticides
...so, just ask yourself which is a BETTER (= more narrow) search term.
well, essentially the entire passage is about biocontrol agents, whereas only small portions (the very top and the very bottom) deal with pesticides. so, think about the pesticides first!

the stuff in the middle of the passage has nothing at all to do with pesticides, so you needn't even bother reading those parts.

[rohit.manglik]

Hi @jlucero,

For post at https://www.manhattanprep.com/gmat/forums/gmat-prep-rc-more-selective-than-most-chemical-pesticides-t20370.html

Can you please explain "this is a case of causation rather than correlation." in more detail.

What can be the other causes?

It looks like we have this posted somewhere else and since it's a GMAT Prep answer, we have to accept it as truth.

http://www.manhattangmat.com/forums/one ... 13510.html

Here's my crack at A vs E:

virus was introduced // rabbit population went down // open ground went down (since rabbits were eating plants) // fewer ant nests // butterflies killed off

A) correct- this is the less specific of the two since it just equates two events- a butterfly's survival with having a certain population of rabbits (greater than what happened after the virus was introduced)

E) incorrect- the biocontrol agent COMPETED with the butterfly. This isn't stated- this is a case of causation rather than correlation.

[tim]

The biocontrol agent was introduced, and also the butterfly population suffered. When two things both happen, this is a correlation. We cannot infer causation unless we can definitely conclude that one thing absolutely affected the other. There is nothing in the passage that states for certain that the biocontrol agent was directly responsible for the extinction, because the butterflies could have gone extinct for another reason while the biocontrol agent thing was happening. It doesn't matter what the other causes are, only that there COULD possibly be other causes.

[AnkurA374]

Hi, can you please tell me if there is any opinion by the author here (something that the author believes in, not something that the author knows is true based on facts / evidence)

e.g. Would you call "The paucity of known extinctions or disruptions resulting from indirect interactions may reflect not the infrequency of such mishaps but rather the failure to look for or to detect them: most organisms likely to be adversely affected by indirect interactions are of little or no known commercial value and the events linking a biocontrol agent with an adverse effect are often unclear." as something that the author solely believes in (debatable / not based on evidence - unsupported claim)


I feel the bold portion is the evidence on which this is based. So, it shouldn't be an unsupported claim, right?

[RonPurewal]

that's "xxxx MAY NOT yyyy" ... then a COLON (:) ... then FACTUAL EVIDENCE

the significance of "xxxx MAY NOT yyyy" is clear enough—it's something that's suggested by certain evidence, but that isn't certain. hence the "may not" wording.

the colon signifies that an EXPLANATION is coming.

the following explanatory statements are clearly factual.

__

...what's the context of this question? in other words, why are you asking this?

who is trying to say there's an "unsupported claim" somewhere? are you asking about one of the answer choices in a problem?