Which of the following is the correct definition of emotion?

a.an aspect of consciousness characterized by a certain physical arousal involving facial and bodily changes, brain activation, and tendencies toward action, all shaped by cultural rules

b.a set of social and cultural rules that regulates when, how, and where a person may express (or must suppress) feelings

c.an irrational aspect of our mammalian heritage that is distinctive from our rational abilities of cognition

d,the process by which the facial muscles send messages to the brain about bodily changes