Critical Reasoning

When a female fruit fly is placed in a cage with several potential mates, her offspring tend to be stronger than when she is caged with only a single male of average strength. Therefore, the female fruit fly must be able to determine which mate will give her the strongest offspring.
Which of the following, if true, is the best basis for a counterargument against the conclusion drawn above?
(A) The offspring also tend to be stronger when, in a cage containing several female and male fruit flies, the males vary widely in strength and size, from very small and weak to very large and strong.
(B) Given a choice between a male fruit fly of average strength and a relatively weak male fruit fly, the female will mate with the male of average strength.
(C) When caged with just one male fruit fly of average strength, the female produces no fewer offspring than when caged with a variety of potential mates.
(D) Strong male fruit flies produce stronger offspring than do weak male fruit flies, provided that both are mated to females of equal strength.
(E) In a cage containing several male fruit flies, the strongest male does not allow the female to mate with any of the other males.

OA is E

Please explain.

Therefore, the female fruit fly must be able to determine which mate will give her the strongest offspring

E tells us that it is not because the females have a choice to decide the mate but the strongest mate does not allow the female to mate with any of the other males.

E provides an alternate reason and therefore weakens the original argument.

The conclusion is that female fruit fly must know which male to mate with to bear strong off springs. And we have to find a statement that will counter the counclusion, in another words weaken the argument.

A--the question only states that their are different levels of strength among male flies when they are caged with several different female flies. This is irrelevant to the discussion.

B--irrelevant and out of context of the discussion.

C--irrelevant and it strengthens the argument rather than weakening it.

D--This is the trap laid by GMAC. I almost fell for this one. However, the discussion is about male fruit fly strength. Nowhere in the discussion is the female fruit fly strength mentioned. So this is not a good choice.

E--is the correct answer because it provides a logical premise that weakens the arguement.

I hope this helps.

Andrew

Agree with mbadrew and cramya. Has to be E.

Agree with you guys. i go with E

Argument : Female will select the Male

Option (E) : Correct Answer - The Strongest Male will eliminate the others - so the females don't have the choice, therefore weakens the conclusion

Other Options : Irrelevant