Activating the muscles involved in smiling may actually make us feel happier. this is an example of (the)

Activating the muscles involved in smiling may actually make us feel happier and this is an example of Facial feedback effect . The facial feedback effect states that skeletal muscle feedback from facial expressions can influence emotional experience. Facial movement plays a causal role in regulating emotional experience and behavior.

Cand d are correct because the rest are just showing your mistakes and you don’t want people who are reading a summary you wrote to see all the mistakes you made.