Correct answer: Kb31...Kf5 2.e4# 1.Kb5?? zz 1...Kf5 2.e4# 1...Kd5 2.e4#/Bf3# but 1...Kd3! 1.Kb3! zz 1...Kf5 2.e4# 1...Kd3 2.Bc2# 1...Kd5