official explanation:

The first two sentences of the argument address the currently-held theory that certain physical features that serve only to indicate "attractiveness" have developed in order to help those males distribute their own genes more widely. For example, a male peacock's plume of tailfeathers does not actively help him to survive; the theory holds that it helps him to procreate by attracting females. The first highlighted portion explains to us how this theory works.

The final two sentences of the argument introduce information that contradicts this theory. In this particular species of bird, the homelier birds are better at passing on their genes than the attractive birds. The second highlighted portion provides an example of the specific research results that contradict the theory.

(A) The first highlighted statement is not a conclusion; it is an explanation of how the theory works. The second highlighted statement is not a contention (or conclusion); it simply presents new evidence and allows the reader to draw a conclusion.

(B) The two highlighted statements address opposite sides of the argument, but this choice says that the second statement supports the theory advanced by the first statement.

(C) CORRECT. The first highlighted statement explains how the theory is thought to work and the second highlighted statement presents research results that contradict this theory.

(D) Nothing in the argument indicates that the long-held theory discussed in the first two sentences is not still prevalent. Indeed, the research that contradicts the theory was only discovered "recently." In addition, the second highlighted statement does not introduce a new theory; it simply presents research results that contradict the original theory.

(E) The scientist does not completely disprove the long-held theory; she merely presents one piece of data that does not support the theory. In addition, the second highlighted statement does not introduce a new theory; it simply presents research results that contradict the original theory.