The Disappearance of the Proleg Behaviors in the Tobacco Hornworm

The disappearance of the proleg behaviors in the tobacco hornworm (Manduca sexta) and the disappearance of leg movements associated with hatching in the domestic chicken (Gallus domesticus) differ from one another in that

A) the loss in hornworms is due to a sudden drop in hormones, while in chickens it is due to degeneration resulting from disuse.
B) the loss in hornworms is due to degeneration resulting from disuse, while in chickens it is due to a sudden drop in hormones.
C) the loss in hornworms is due to modification to serve other patterns of behavior, while in chickens it is due to the dismantling of the underlying neural circuitry.
D) the loss in hornworms is due to the dismantling of the underlying neural circuitry, while in chickens it is modified to serve other patterns of behavior.