Which drug class does hydralazine belong to?

A. Angiotensin receptor blocker: Angiotensin receptor blockers (ARBs) work by blocking angiotensin II receptors to relax blood vessels and reduce blood pressure. Hydralazine does not act on the renin-angiotensin system, so it is not classified as an ARB. B. Diuretic: Diuretics lower blood pressure by promoting the excretion of sodium and water through the kidneys. Hydralazine does not have diuretic effects and does not alter fluid balance in this way. C. Alpha receptor blocker: Alpha blockers reduce blood pressure by inhibiting alpha-adrenergic receptors in blood vessels, causing vasodilation. Hydralazine’s mechanism is direct smooth muscle relaxation, not alpha receptor antagonism. D. Vasodilator: Hydralazine is a direct-acting vasodilator that relaxes arteriolar smooth muscle, leading to decreased systemic vascular resistance and lower blood pressure. It is primarily used in hypertension management and sometimes in heart failure.