Column 3 is the optimal move for multiple reasons: 1) It blocks a potential vertical win for my opponent who already has 2 X pieces in that column, 2) It creates a horizontal connect-3 for me with my O pieces at (2,2) and (2,5), putting pressure on my opponent, and 3) It develops my position in the center of the board, which typically provides more winning opportunities than the edges. This move is both defensive and offensive.