How does a diuretic affect blood pressure?

A diuretic affects blood pressure primarily by promoting the excretion of sodium and water from the body, leading to a decrease in blood volume. When diuretics are administered, they act on the kidneys to increase the production of urine, which facilitates the removal of excess sodium and fluid. As sodium is excreted, water follows osmotically, which helps reduce the overall volume of blood circulating in the blood vessels.

This reduction in blood volume directly leads to lower blood pressure, as there is less pressure exerted against the arterial walls. This mechanism is particularly important in the management of conditions such as hypertension and heart failure, where fluid overload can exacerbate symptoms and complicate treatment. Thus, the correct answer aligns well with the established pharmacological action of diuretics in lowering blood pressure through volume reduction.