In the old west, a marshal riding on a train traveling 50m/s sees a duel between two men standing on the earth 50m apart parallel to the train. The marshal's instruments indicate that in his reference frame the two men fired simultaneously. (a) Which of the two, the first one the train passes (guy A) or the second (guy B), should be arrested for firing the first shot? (b) How much earlier did he fire? (c)Who was struck first? (d) Who is struck first according to the marshal and explain why?