Why Would Holding a Pencil in Your Front Teeth (Vs

Why would holding a pencil in your front teeth (vs. with your lips) make you feel happy?

A) You would know that you were in effect smiling and you have learned that a smile indicates happiness.
B) The muscle activity involved in this action causes vascular changes that reduce brain temperature.
C) The activity would make you self-conscious, which often results in nervous laughter.
D) This activity is similar to the movements involved in feeding during infancy.
E) You would need some rationale for engaging in the activity, and with the lack of any other explanation you would focus on your mood.