Correct answer: Bf31...Kb3 2.Bd1# 1...c3 2.R:c3# 1.a4?? zz 1...Kb3 2.Bd1# 1...c3 2.R:c3# but 1...b:a4! 1.Kf1?? zz 1...Kd2 2.Ra2# 1...Kb3 2.B