The correct answer is D) A round turn, figure eights, and a half-hitch. This method is the proper way to fix running rigging (such as sheets, halyards, or downhauls) to a cleat. The round turn provides a secure initial attachment, the figure eights distribute the load evenly on the cleat, and the half-hitch adds a final locking mechanism to prevent the line from slipping. The other options are incorrect because they do not fully secure the line. Half-hitches alone (option B) may not be enough to hold the load, a single round turn (option C) lacks the locking mechanism of the half-hitch, and a half-hitch after the round turn (option A) does not distribute the load as effectively as the figure eights.