Which autonomic system conserves energy by returning the body to a normal activity level through a lowered heart rate and blood pressure? a peripheral nervous systemb sympathetic nervous systemc somatic nervous systemd parasympathetic nervous system

The parasympathetic nervous system conserves energy as it slows down heart rate, increases intestinal and glandular activity, and relaxes the sphincter muscles of the gastrointestinal tract. It gets the nickname "rest and digest" for doing exactly so. Typically most active when sleeping, however is also the explanation for post-prandial fatigue, or being tired after eating (especially a large meal).