Elizabeth was driving on the freeway when a car passed abruptly in front of her and almost hit her vehicle. As a result of the stress produced by this incident, her heart rate increased and she felt nauseous due to the slowing of intestinal activity. Which of the following neurotransmitters is responsible for Elizabeth's increase in heart rate and slowing of intestinal activity?
A. Glutamate
B. Dopamine
C. Norepinephrine
D. GABA