Final answer:
The correct answer is the Parasympathetic nervous system. It is responsible for regulating bodily functions during restful periods.
Step-by-step explanation:
The correct answer is C) Parasympathetic nervous system.
The parasympathetic nervous system is responsible for regulating bodily functions during restful periods, as mentioned in the provided information. When Bob lifted his foot off the tack before realizing he had stepped on it, it was an unconscious action controlled by the parasympathetic nervous system.