When ducklings are exposed to music

When ducklings are exposed to music, they gain about six percent more weight for a given amount of feed than ducklings that are not exposed to music.

Which of the following, if true, most helps to explain the extra weight gains referred to above?

A) Music played for ducklings must be kept at a low level because ducklings exposed to loud music gain less weight than ducklings exposed to no music.
B) Ducklings exposed to classical music gained more weight than ducklings exposed to popular music.
C) Ducklings are less active when they hear music so that less of the food they eat Is expended in movement, and more contributes directly to the ducklings' growth.
D) When ducklings gain six percent more weight on a given amount of grain, the farmers' profits increase because they can spend less money on grain to feed the ducklings.
E) When female ducklings were exposed to music, the percentage of fertile eggs that they laid as adults increased by over 27 percent in comparison to ducklings not exposed to music.