The correct answer is A) The barge may swing too quickly and run over the tug. When towing a barge on a short hawser, attempting to swing the barge quickly can cause the barge to swing too far and potentially collide with the towing vessel. This is the principal danger in this maneuver, as the barge's momentum and the short distance between the tug and barge increases the risk of the barge running over the tug if the swing is too sharp. The other answer choices are incorrect because: B) Capsizing is not the main concern with this maneuver, C) Free surface effect is not the primary issue, and D) Dangerous wakes are a secondary concern compared to the barge directly colliding with the tug.