The answer is C: procedural memory. This is because gymnastics is a task that Arianna has done in the past. It became something her body learned and mastered. She learned HOW TO DO IT. A procedure is "an established or official way of doing something" (Oxford). An explicit memory would be things like your name, close family and friends, birthday, etc.. A sensory memory would be something that someone could sense (see, hear, touch, taste, smell) for a short period of time, but still remember.
