Stan's Wife Is a Victim of a Head-On-Collision That Has

Stan's wife is a victim of a head-on-collision that has left her paralyzed from the neck down and she has fallen into a coma. Her last words to him were that she did not want to live in such a horrible state. Stan's wife's doctor confirmed that there was no hope of recovery. While alone in the room with his wife, Stan places a pillow over her head and suffocates his wife. Stan has committed the act of what type of crime?

A) Involuntary manslaughter
B) Voluntary manslaughter
C) Mercy killing
D) None of the above