Correct answer: Qb11.Bc6+?? 1...Kc4 2.Qc3# but 1...K:c6! 1.Kf6?? (2.Qe6#) 1...c4 2.Qe5# but 1...Kc4! 1.Kf5?? (2.Qe4#/Qe6#) 1...c4 2.Qe5#
