A 66-Year-Old Man with Chronic Hypertension Is Treated with Prazosin $\beta_{1}$

A 66-year-old man with chronic hypertension is treated with prazosin by his physician. The treatment successfully decreases his blood pressure to within the normal range. What is the mechanism of the drug's action?

A) Inhibition of $\beta_{1}$ receptors in the sinoatrial (SA) node
B) Inhibition of $\beta_{2}$ receptors in the SA node
C) Stimulation of muscarinic receptors in the SA node
D) Stimulation of nicotinic receptors in the SA node
E) Inhibition of $\beta_{1}$ receptors in ventricular muscle
F) Stimulation of $\beta_{1}$ receptors in ventricular muscle
G) Inhibition of $\alpha_{1}$ receptors in ventricular muscle
H) Stimulation of $\alpha_{1}$ receptors in the SA node
I) Inhibition of $\alpha_{1}$ receptors in the SA node
J) Inhibition of $\alpha_{1}$ receptors on vascular smooth muscle
K) Stimulation of $\alpha_{1}$ receptors on vascular smooth muscle
L) Stimulation of $\alpha_{2}$ receptors on vascular smooth muscle