A Points an Unloaded Gun at B and Threatens to Shoot

A points an unloaded gun at B and threatens to shoot. Unobserved by A , C, who is B 's wife, witnesses the threat and believes A 's gun is loaded and that B is about to die. C pulls out a gun and shoots and kills A . In this case:

A) C cannot successfully invoke the privilege of defense of others because A 's gun was unloaded.
B) C can successfully invoke the privilege of defense of others because of her reasonable belief at the time she shot A .
C) C is liable because one can use deadly force only to protect himself.
D) C was entrapped into believing her husband was about to be killed, so she has a valid defense.