Correct answer: Rf4-g4 1.Rf4-g4 ! zugzwang. 1...Rg8-f8 2.Qe5*g7 # 1...h7-h5 2.Qe5*h5 # 1...h7-h6 2.Rg4-g6 danger: 3.Rg6*h6