Which Question Would Be Most Appropriate for the Nurse to Ask

Which question would be most appropriate for the nurse to ask a son who is his father's health care proxy to help clarify the father's end-of-life wishes?

A) "Did he ever speak to your mother about his wishes?"
B) "When did your father complete his advance directive?"
C) "Would you tell me in his own words what he said he wanted done at the end of his life?"
D) "Who else was present during the discussion?"