The correct answer is C) terminal gear. Terminal gear refers to the equipment used to control, protect, and connect a towline. This includes items like the towing hook, shackles, and other fittings that connect the tow rope or line to the vessel. The terminal gear is critical for safely and securely towing another vessel or object. The other answer choices are incorrect because: A) a cat head is a spar or davit used for handling lines, anchors, or small boats, not specifically for towing; B) a level wind is a mechanism on a fishing reel that evenly distributes line on the spool, unrelated to towing; and D) a poured socket is a method of attaching wire rope, not the equipment used to connect a towline.