Correct answer: Nb31. B:b4? [2. Q:c5#] 1. ... e5 2. Rb7# 1. ... c:b4 2. Rc2# But 1. ... K:b4! 1. B:d4? [2. Q:c5#] 1. ... e5 2. Rf4# 1. ... c:d4 2. Rc2#