Correct answer: Rb41.Rh3?? zz 1...Kb4 2.d4# but 1...b4! 1.Rh2?? zz 1...Kb4 2.d4# but 1...b4! 1.Rh1?? zz 1...Kb4 2.d4# but 1...b4! 1.Rh5?? zz 1...Kb4 2.d4