The nervous system is a part of the autonomic system that conserves energy by returning the body to a normal activity level through a lowered heart rate and blood pressure.

The correct answer is: parasymphatetic.

Explanation:

The Parasympathetic Nervous System (PNS) is one of the two divisions of the autonomic system, which is the system that regulates all our bodily functions, like heart rate and peristalsis.

While the Sympathetic Nervous System is responsible for our bodies' "fight-or-flight" response, the PNS activates when we are doing relaxing activities, such as eating or resting. This explains why, for example, our heart rate decreases when we're at ease.