A Nurse Answers the Telephone Hotline and Was Able to Talk

A nurse answers the telephone hotline and was able to talk to four different callers. Which comment should be given the highest priority?

A) "If things don't get better, I will jump over a cliff."
B) "I feel so lonely. I can't go on."
C) "I have a loaded gun and I think I will use it."
D) "My wife has a terminal illness and I can't accept that I will lose her."