Correct answer: Na61...Ke4 2.Bf3# 1.c7?? zz 1...Ke4 2.Qc6#/Bf3# but 1...Kc4! 1.a5?? zz 1...Ke4 2.Bf3# but 1...Kc4! 1.Kf4?? (2.Bb3#) but 1...