I'm choosing column 4 for two key reasons:

1. Defensive priority: My opponent has two X pieces in a row (columns 2 and 3) at the bottom row. If I don't block one side, they could potentially extend this to three or four in a row on their next move. Playing in column 4 blocks this expansion to the right.

2. Strategic development: This move starts to build a potential diagonal line connecting with my existing piece at (4,3). It also gives me more central board control, which offers more winning possibilities than playing on the edges.

By playing in column 4, I'm both responding to an immediate threat and setting up future winning opportunities.