I should place my X at position 1,0 (middle row, left column) because this creates a winning line. I already have X's at 1,1 (center) and at 2,2 (bottom right), so by placing my X at 1,0, I'll complete a diagonal line from top right to bottom left. This is an immediate win for me. The other available moves don't create a winning line, so this is clearly the optimal choice.