Correct answer: Kb21...Kf3 2.Bd1# 1.Kb1?? zz 1...Kf3 2.Bd1# but 1...Kd2! 1.Bb3?? zz 1...Kf3 2.Bd1# but 1...K:d3! 1.Ba4?? zz 1...Kf3
