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.