Looking at the board, I notice my opponent has X's at positions (0,1) and (1,1), creating a vertical threat in the middle column. If they place their next X at position (2,1), they would win immediately. I need to block this threat by placing my O at (2,1).

While I could start building my own winning line in the left column (where I already have an O at 0,0) by playing at (1,0) or (2,0), blocking an immediate threat takes priority. After this defensive move, I can work on creating my own winning opportunities in subsequent turns, potentially through the left column or by creating new threats elsewhere on the board.