Q18 - Advertisement: Attention pond owners!

[c.s.sun5]

Can someone explain to me why the answer is (E) and not (A)? I marked (A) for my answer because I thought the conclusion was based on the fact that you want to lower the population of moquitoes in the pond.

Thanks!

[aileenann]

(A) is relevant, but it's not really something we need to be true. In particular the word "most" in (A) makes it a lot stronger than we need. We just need to conclude that you can "greatly reduce" mosquito populations - we don't care whether you are using the method that will most reduce mosquito populations.

On the other hand, (E), though it seems a little off base at first, has to be true for this argument to hold. To see why, try negating it. If we imagine that fish, frogs, and other god things do depend on the larvae, we'll see that while you may reduce mosquitoes, you will also reduce the populations of these other species - contrary to the argument's conclusion!

Does that make sense? Are you familiar with using the negation test to check an answer choice?

[c.s.sun5]

Yup, I know the negating method, it's just that sometimes, the answer choices still confuse me.

Thanks for the clarification!

[bharbin1544]

By and large, it has been difficult for me to anticipate answer choices on NA question types. However, this one was easy for me to see. Heres how I see the argument:

P: Use BTI to destroy pesky mosquito larvae
C: Greatly reduce populations of the pesky mosquitos that hatch in the pond. All this while not harming or diminishing the populations of frogs, fish or beneficial insects that are wanted.

As soon as I finished the argument, I knew that the conclusion needed a "shield" from attacking the assumption. By assuming (E), you are ensuring that the conclusion stays together by saying that the fish, frogs and beneficial insects will not be harmed if all the larvae are eliminated. But, by negating this statement, you're essentially saying that the fish, frogs and beneficial insect will be adversely affected by the elimination of the larvae. Hence, the argument falls apart.

[jiangziou]

Is "So by using BTI....you can greatly reduce..without diminishing" a conditional statement?

I know "without" can introduce necessary conditions, for example:

Humans cannot survive without water.
Survive--->Water