Correct Answer: A

Rationale: Enalapril is an ACE inhibitor that blocks the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor. This results in decreased vascular resistance, reduced blood pressure, and diminished aldosterone secretion. The observed normalization of BP reflects the expected therapeutic outcome. ACE inhibition also promotes natriuresis, contributing further to its antihypertensive effect. Unlike calcium channel blockers, ACE inhibitors act via the renin-angiotensin-aldosterone system and are particularly beneficial in patients with hypertension and heart failure.

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