Diagram 11 is repeated on the left. . Black cannot capture the white knight that is putting his king in check. It is no use interposing his bishop because the knight can jump. He must move his king. In diagram 12 he has played Kg7. Kf7 or Kh8 would also get the king out of check.
Diagram 11 Diagram 12
There is only 1 way for white to get out of check. Can you find it?
Diagram 13
