Correct answer: O-O-O1...Kc2 2.Qc4# 1.Rb1+?? 1...Ka3 2.Nb6#/Nc3#/Nc5# 1...Ka2 2.Nc3# but 1...Kc2! 1.O-O-O! zz 1...Ka3/Ka2 2.Nc5#
