Your Patient Is Found Sitting on the Edge of the Bathtub

Your patient is found sitting on the edge of the bathtub with cool, diaphoretic skin. She states she became lightheaded and nearly "passed out" while vomiting. Your cardiac monitor shows a sinus bradycardia at a rate of 48. Which of the following is most likely?

A) Sick sinus syndrome
B) Use of sympathomimetic medications
C) Disease of the cardiac conduction system
D) Increased parasympathetic tone