I'm choosing column 4 because it blocks my opponent's potential horizontal connection. Right now they have X pieces at positions (5,3) and (5,4). If I place my O at column 4, it prevents them from building on their horizontal line from the right side. Additionally, this position is centrally located, which is strategically advantageous in Connect Four as it opens up more winning possibilities in multiple directions (horizontally, vertically, and diagonally). By playing in the middle area of the board, I'm also setting myself up for more flexible future plays.