D Kills V by Shooting Him in the Back Mistakenly

Multiple Choice

D kills V by shooting him in the back mistakenly believing that his own life is in danger from V. Which of the following will provide the defence of self-defence:

A) The use of force must be reasonable on the facts as D honestly believed them to be.
B) The use of excessive force must be necessary on the facts as D believed them to be.
C) The use of excessive force is never permitted.
D) D must establish that anyone would have made the same mistake.