Correct answer: Ra31...K:d3 2.O-O-O# 1...c:d3 2.Ra4# 1.Rca2?? zz 1...K:d3 2.Rd1#/O-O-O# 1...c:d3 2.Ra4# but 1...c2! 1.Re2?? zz 1...K:d3 2.Rd1# 1...c:d3 2
