As a Male Silkworm Moth Nears a Female That Is

As a male silkworm moth nears a female that is releasing pheromone,

A) he can locate the female by following a concentration gradient of the pheromone.
B) the action potentials in his antennal nerve decrease.
C) fewer pheromone-sensitive hairs are stimulated per second.
D) the female starts to release more pheromone.
E) he switches from pheromone detection to hearing for locating the female.