What nervous system gets your body ready for action in an emergency by increasing adrenalin and slowing down digestion.?

The correct answer is the sympathetic nervous system.

The sympathetic nervous system is a division of the autonomic nervous system that is responsible for the body's "fight or flight" response. When the sympathetic nervous system is activated, it increases heart rate, blood pressure, and breathing rate, and dilates the airways. It also slows down digestion and shunts blood flow to the muscles. These changes prepare the body for physical activity and help it to cope with stress.