To block my opponent from making a line of 4 pieces and set up future winning opportunities, I should place my piece in column 3, but since it's not available, I'll choose the next best option which is to place my piece in a position that could potentially create a line of 4 pieces for me while also considering the ability to block my opponent. Given the current state of the board and available columns, the best option seems to be column 2 because it allows for the potential to create a line and doesn't immediately give my opponent an advantage.