Charlie Is Driving Down the Street When He Witnesses Two

Charlie is driving down the street when he witnesses two men assaulting a third man. This makes Charlie very mad. Charlie stops his car, pulls a baseball bat from the trunk, and tries to get the assailants to stop their attack. In the ensuing scuffle, Charlie fatally strikes one of the assailants with the bat. What defense should Charlie use in court?

A) necessity
B) duress
C) not criminally responsible on account of mental disorder
D) self-defence