Answer:
Relaxing the smooth muscles in arteries would lower down the blood pressure.
Explanation:
Smooth muscles are present in lining of blood vessels. Relaxing the smooth muscles in arteries causes vasodilation, that is, the cavity of arteries is widened. Dilated arteries allow more blood to pass through them and lower down the blood pressure. Constriction of smooth muscles of arteries causes vasoconstriction and increases blood pressure.