Malcolm is studying alone in his room late at night when he hears a loud noise downstairs. his heartbeat increases significantly and his breathing becomes shallow. he wonders if a burglar has entered the house and decides to investigate. when he gets downstairs he discovers his cat has knocked over a plantstand. his body begins to relax and return to normal.
which part of his nervous system is responsible for returning malcolm to a normal state?

a) spinal cord
b) somatic nervous system
c) sympathetic nervous system
d) parasympathetic nervous system