Which part of the autonomic system is most likely to be dominant while someone is napping after lunch?

parasympathetic nervous system

Explanation:

The autonomic nervous system has two divisions: the parasympathetic nervous system and sympathetic nervous system. The parasympathetic nervous system is responsible for "rest and digest" activities while the sympathetic nervous system prepares the body for "fight and flight" activities. Hence, the parasympathetic nervous system dominates during napping.