Correct answer: Nb51...Kd6 2.Q:e6# 1.Rf4?? (2.Q:e6#) but 1...Kc4! 1.Ne2?? (2.Qd4#) 1...e5 2.Qc6# but 1...Kd6! 1.N:e6?? zz 1...Kd6 2.Rd2#
