How do ACE inhibitors primarily reduce blood pressure?

A. By decreasing afterload: ACE inhibitors indirectly reduce afterload by causing vasodilation, but the primary mechanism is through inhibition of angiotensin II formation. The decrease in afterload is a consequence, not the main action. B. By removing excess fluid: ACE inhibitors do not directly remove fluid. Diuretics achieve fluid removal. ACE inhibitors may reduce fluid retention indirectly by decreasing aldosterone levels, but this is secondary. C. By increasing heart rate: ACE inhibitors do not increase heart rate. Heart rate may remain unchanged or even decrease slightly due to improved cardiac efficiency. Tachycardia is not a mechanism of action. D. By blocking the conversion of angiotensin I into angiotensin II: ACE inhibitors prevent the formation of angiotensin II, a potent vasoconstrictor, which leads to vasodilation and reduced systemic vascular resistance. This action lowers blood pressure and reduces workload on the heart.