Good Morning Puzzlers, Once again, I urge you to read Paul's excellent problem analysis to understand this problem thoroughly. But to confirm the answer: The best move is: 1. c6 Principle: The pair of White Bishops bearing down on the Black Queenside are very powerful. 1. c6 forks Rook and Pawn! If Black takes the Pawn with 1... bxc6, 2. Bxc6 forks the Rooks. If Black moves the Rook, 2. cxb7 and the other Rook has no place to hide.