Adult Male Humans Generally Have Deeper Voices Than Do Adult

Adult male humans generally have deeper voices than do adult female humans, as the direct result of higher levels of testosterone causing growth of the larynx.
-If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females, and increasing larynx size in adult males, then

A) sexual dimorphism was developing over time in these species.
B) intrasexual selection seems to have occurred.
C) the "good genes" hypothesis was refuted by these data.
D) stabilizing selection was occurring in these species concerning larynx size.
E) selection was acting more directly upon genotype than upon phenotype.