Answer:
VIII vestibulocochlear nerve, easy to remember because of cochlear being in the word, cochlear implants have to do with hearing loss, yw :)
Things like running around the house will not be done as a kid, since as a kid you were way more energetic, but now as a young adult that may not be the case.
The answer would be : C. Increase the intensity of cardiovascular workouts
cardiovascular workouts are the best one to increase the target heart rate. By increasing it's intensity, Xavier will increase his heart rate to the point where he managed to achieve his target
hope this helps