Which of the Following Is an Example of a Serviceable

Which of the following is an example of a serviceable habit, as described originally by Charles Darwin?

A) Animals learning and habituating to their species' emotion expressions through experience
B) Through evolution, a random and non-functional body gesture becomes a communicative signal for a species
C) Facial expressions of disgust are thought to originate from actions that expel toxic substances
D) Fearful animals often have wide eyes because it is recognized across species as a sign of fear