Correct answer: f41...Nd6/Nd8 2.O-O-O# 1.R:f7?? (2.O-O-O#) but 1...B:f7! 1.Bd5?? zz 1...Nd6/Nd8 2.O-O-O# but 1...e4! 1.Bc6?? zz 1...Nd6/Nd8 2.O-O-O#
