The correct answer is A) reduce sail area exposed to the wind. When experiencing heavy winds, reducing the sail area exposed to the wind through reefing (partially furling) the sails is the appropriate action. This decreases the amount of sail area that can catch the wind, thereby reducing the heeling force on the vessel and keeping it more stable and manageable in the heavy conditions. The other options are incorrect because: B) removing tension on the sheets would not reduce the sail area; C) allowing the sails to catch more wind would increase the heeling force; and D) bringing the sails parallel to the wind would essentially deprive the sails of any wind, which is not the desired outcome in heavy weather.