People diagnosed with OCD suffer from compulsions. Which of the following is a compulsion?

a. Renee persistently thinks about the possible death of her loved ones.

b. Eric frequently worries that there may be germs on his hands.

c. Brianna has an ongoing worry that she might have left the oven on at home.

d. Stefan often feels great anxiety if things are not in exact order in his room.

e. Tyrik flips the light switch on and off seven times each time he walks in the front door.