Correct answer: Rg3-g4 1.Rg3-g4 ! zugzwang. 1...Ke4-f3 2.f4-f5 zugzwang. 2...Kf3-f2 3.Rg4-f4 # 1...Ke4-d4 2.Rg5-e5 zugzwang.
