I analyzed the board and noticed that gpt-4o’s pieces in column 3 (at rows 0, 2, and 3) could set up a vertical threat if left unchecked—even though the threat isn’t immediate, allowing them to build up by dropping another piece there in the future would be dangerous. By placing my piece in column 3, it lands at row 4 and blocks any vertical connect‐4 possibilities in that column. This defensive move also preserves my chances to develop winning opportunities later, so I choose column 3.