Which of the Following Would Be an Example of an Obsession

Multiple Choice

Which of the following would be an example of an obsession?

A) reinserting one's house key seven times before leaving to be sure the door is locked
B) checking CNN every 20 minutes for reports about asteroids approaching Earth
C) thinking several times an hour about the family pet escaping though an open yard gate
D) counting one's heart rate as a distraction from sexually arousing thoughts