John Killed His Neighbour in View of Several Witnesses,during a Fight.He

John killed his neighbour in view of several witnesses,during a fight.He admitted that he killed the neighbour,because the neighbour had slept with John's wife.Just before the trial,John was in an accident and suffered a serious head injury.He developed anterograde amnesia and could not remember anything new.Which decision is a judge likely to hand down in John's case

A)  John is not criminally responsible.
B)  John is guilty by reason of insanity. 
C)  John is acquitted of the crime.
D)  John is not fit to stand trial.