Correct answer: Na61...Kb8 2.Qb6# 1.Nb5?? zz 1...Kb8/Ka8 2.Qc8#/Qa7# but 1...Ka6! 1.Bd5+?? 1...Kb8 2.Na6# but 1...Kc8! 1.Kf4?? zz
