Correct answer: N:b71...Kc6 2.B:b7# 1.Bc7?? zz 1...Kc6 2.B:b7# but 1...Ke6! 1.Kd8?? zz 1...Kc6 2.B:b7# but 1...Ke6! 1.f7?? zz 1...Kc6 2.