In a two player strategy game, players take turns shading one or two circles on a board. The goal of the game is to shade the last of the ten circles on the board. In the game below, Player A is shading in a solid colour, and Player B is shading with lines. It's now Player B's turn. How many circles should Player B shade to guarantee a win? Explain why this move will guarantee a win, using diagrams if necessary. <>