I'm selecting position 1,2 (middle-right) because it creates two possible winning paths for my X symbols. By placing my X here, I'm setting up a potential diagonal win from bottom-left to top-right, and also a potential horizontal win across the middle row. This forces my opponent to block one of these threats on their next move, allowing me to potentially create another winning opportunity. It's an offensive move that gives me multiple paths to victory rather than just responding to the opponent's O in the top-left.