The correct answer is C) They are used to steady a lifeboat when lowered. Frapping lines are used to steady a lifeboat or other davit-launched survival craft as it is being lowered into the water. They help control the motion of the boat and prevent it from swinging excessively, which could be dangerous during the lowering process. This is a standard safety practice required by the Coast Guard regulations for any vessel that carries davit-launched survival craft. The other answer choices are incorrect. A) is incorrect because frapping lines are not normally attached to the davit span. B) is incorrect because frapping lines are not used to clear the puddings (protective coverings on the davit arms). D) is incorrect because frapping lines are required on all types of davits, not just radial davits.