Correct answer: Bg51. Bg5! waiting 1. ... d5 2. Ng4 [3. Nh6 [4. Nf7#] 3. ... g:h6 4. B:f6#] 2. ... f:g5 3. Ne5 ad lib 4. Nf7# 2. ... f5 3. Nh6 [4. Nf7#] 3. ... g:
