Adult Male Humans Generally Have Deeper Voices Than Do Adult

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from

A) pansexual selection.
B) directional selection.
C) disruptive selection.
D) stabilizing selection.
E) asexual selection.