The correct answer is A) All barges in the tow must be lighted. This is the correct answer because the International and Inland Navigation Rules require that when towing more than one barge astern at night, all barges in the tow must display the appropriate navigation lights. The lights help to clearly indicate the presence, size, and configuration of the tow to other vessels in the area. The other options are incorrect because they do not fully comply with the lighting requirements. Option B is incorrect as it only requires the first and last barges to be lighted, while option C is incorrect as it only requires the last barge to be lighted. Option D is incorrect as it exempts unmanned barges from the lighting requirement, which is not the case.