Henry Is Walking Down the Street When He Hears a Voice

Henry is walking down the street when he hears a voice coming from a ground floor apartment.The voice is saying "Help! Help!" Henry,a reserve deputy constable,rushes to the door and knocks.No one answers.He then kicks the door in and discovers an elderly woman sitting in a chair watching a movie on television.She has the sound turned up because she is hard of hearing.She apparently did not hear Henry's knock.The cry for help was the sound from the television program.Were the elderly resident to seek to file criminal charges against Henry for damaging the front door and trespassing in her apartment,Henry's best strategy would be to assert the defense of:

A) mistake of fact.
B) mistake of law.
C) necessity.
D) public duty.