Identify the nervous system responsible for calming the body and conserving energy.

in complete sentences ? : )

The nervous system is the organ system responsible for the many neural activities in the human body which includes the interaction of the brain and the spinal cords with the nerve cells in the body or the periphery. 
Two dividions are the central nervous system: brain and spinal cord
Peripheral Nervous system: neurons

Peripheral Nervous system has autonomic and somatic nervous system

Autonomic NS has two sympathetic and parasympathetic.

The parasympathetic nerovous system is responsible for reducing intensity of one's behavior and soothes the whole body system.