Final answer:
Parasympathetic stimulation and certain medications can cause first-degree AV block, and one medication that could be evaluated is Inderal, a beta-blocker.
Step-by-step explanation:
Parasympathetic stimulation can cause first-degree AV block. One possible medication to evaluate is Inderal, which is a beta-blocker. Beta-blockers work by blocking the beta receptors associated with vasoconstriction and cardioacceleration. By blocking these receptors, heart rate is slowed down, potentially leading to first-degree AV block.