Which plot is the best example of a tragedy?

A. An old man tells his grandson the heartbreaking story of his experiences as a soldier in world war 2.

B. A little girl is lost on the streets of New York City, and her parents work to find her as quickly as possible.

C. The chief of police loses his job and the respect of his family after his lies and criminal connections are exposed.

D. A couple struggles to stay together as their families and careers manage to keep them apart.