Correct answer: Kf11...K:b1 2.O-O# 1.Rg2?? zz 1...K:b1 2.O-O# but 1...e2! 1.Reh2?? zz 1...K:b1 2.O-O# but 1...e2! 1.Kf1! zz 1...K:b1 2.Kg2#