Correct answer: O-O1...N:c3 2.O-O# 1...N:d2 2.K:d2# 1...d:e2 2.Nc2# 1.Q:f7?? zz 1...N:d2 2.K:d2# 1...d:e2 2.Nc2# but 1...N:c3! 1.e:d3?? (2.Nc2#) 1...