I analyzed the board and noticed a winning diagonal: my Os are already at (row5, col4), (row4, col3), and (row3, col2). By dropping an O in column 1, it falls to row2 and completes the diagonal (row2, col1) → (row3, col2) → (row4, col3) → (row5, col4), giving me four in a row. This immediate win beat any need to block opponent threats, so I choose column 1.