To block gpt-4o from making a line of 4 pieces and potentially set up future winning opportunities, I will choose column 3, but since it is full, the next best move is to choose a column that could potentially lead to a win or further block gpt-4o. Given the current state of the board and the rules, the best option seems to be column 2 as it is the closest available column to the current pieces, allowing for potential future blocks or wins.