Thanks Xavier! After looking at the posted answers and question to compare, we can see that since he wants to increase his Heart Rate. A anaerobic workout is a short burst of energy, so it wouldn't be a good fit. Doing fewer aerobic workouts would lower it even more, so he shouldn't do that either. Increasing the intensity sounds about right, but we have to see our final choice. Decreasing intensity of a cardiovascular workout would also cause a larger decrease, so we can now see that answer is choice C.
