Cacioppo and petty (1981) recorded facial muscle activity of college students as they listened to a message with which they agreed or disagreed. the results of this study indicated that listening to a(n) message increases activity in the
a. disagreeable cheek muscles
b. disagreeable chin muscles
c. agreeable cheek muscles
d. agreeable muscles in the forehead and brow area

c. An agreeable message ; increases cheek muscles

Explanation:

When we agree with the message we are most likely to be happy and to smile as the result which will relax our cheeks muscles , one can even see the movement in our cheeks.

However if we don't agree with the message which may be sadning or distressing the muscles that get affected are our forehead and brow area because we are very likely to frown and the muscles in these areas get affected

elastic potential energy