When a female fruit fly is placed in a cage with several potential mat

E for me.

It is not the female fly who determines which mate will give the strongest offspring but it is the strongest male fly who does not allow the female to mate with anyone else.

+ E

Conclusion says that the female fruit fly must be able to determine which mate will give her the strongest offspring. For Counter argument we need to look for a choice such as female fruit fly can't distinguish the strength. Or probably male dominate on the basis of strength. Only E is on these lines. Easy one.

E for me

Its like X causes Y
but we gotta find an option that says Y causes X

Quote:

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 counter-argument against the conclusion drawn above?

Our author concludes that a female fruit fly clearly knows how to pick her partner (going after the one that will give her offspring the best chance to survive). He supports this thought process by expressing the result in two “studies”. In one study with multiple mates, her babies are stronger than in another study, when she is stuck with an average mate.

He seems to assume that there is no alternative phenomenon, what if it’s the male that chooses her first? Or that her offspring are just stronger by chance (and that the potential mates she’s stuck with are also just average)? Of what if her offspring’s strength is affected by the number of males in the vicinity….?

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 the very small and weak to a very large and strong.
This answer choice is basically another premise…but it doesn’t support or weaken the idea that the female fly DETERMINES her strong mate.

B Given a choice between a male fruit fly of average strength and relatively weak male fruit fly, the female will mate with the male of average strength.
This would strengthen the conclusion…since the female fly is determining her offspring’s fate.

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 males.
The number of offspring produced is not the question. We care about how it affects the strength of them! Irrelevant.

D Strong male flies produce stronger offspring than do weak male fruit flies, provided that both are mated to females of equal strength.
This also might strengthen the argument that the female might also partake in the choosing.

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.
Ah, the alpha male does the choosing. This must be it. This is the best weakener.

Understanding the argument -
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. - Fact
Therefore, the female fruit fly must be able to determine which mate will give her the strongest offspring. - Conclusion. Meaning that the Fruit Fly (FF) has the ability to determine which mate will give her the strongest offspring, and she chooses that.

Option Elimination - Weaken

(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. - Strengthener.

(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. - Strengthener.

(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. - The number of offspring is out of scope.

(D) Strong male fruit flies produce stronger offspring than do weak male fruit flies, provided that both are mated to females of equal strength. - The strength of females is out of the scope of this argument.

(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. - Ok. So its other way around not that the FF can determine. Weakener. Ok.