Final answer:
The effect of ACE inhibitors is to cause option D) vasodilation of blood vessels, leading to a reduction in blood pressure by preventing the formation of the vasoconstrictor angiotensin II.
Step-by-step explanation:
The effect of ACE (angiotensin-converting enzyme) inhibitors is the option D) vasodilation of blood vessels. These drugs work by blocking the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor that increases blood pressure through the narrowing of blood vessels. By inhibiting the formation of angiotensin II, ACE inhibitors prevent vasoconstriction, leading to vasodilation which results in lowered blood pressure.