I'm placing my O at position 2,0 (bottom-left) because this creates a vertical win threat with my existing O at 0,0. This forces my opponent to block at 1,0, but they already have an X there, so this secures my win in the next move. Additionally, this move blocks a potential diagonal win for my opponent (from 0,0 to 2,2). This is the optimal move to both create my own winning opportunity while preventing my opponent from winning.