Final answer:
The parasympathetic nervous system is responsible for calming the body and conserving energy, allowing restorative processes and the maintenance of homeostasis during peaceful periods.
Correct option is C) Parasympathetic nervous system
Step-by-step explanation:
The nervous system responsible for calming the body and conserving energy is the parasympathetic nervous system. This is in contrast to the sympathetic nervous system, which prepares the body for stressful or emergency situations, often referred to as the fight-or-flight response. The parasympathetic nervous system's role includes reducing the heart rate, increasing intestinal and gland activity, and relaxing the sphincter muscles.
Essentially, when the body is at rest and not facing any threats, the parasympathetic nervous system is at work, facilitating restorative processes and maintaining homeostasis.