Answer:
The correct option is;
D. The nervous system signals smooth muscles in the blood vessels to contract to increase blood pressure
Explanation:
The contraction or relaxation of the vascular smooth muscles lead to the blood vessel volume change and blood pressure change such that the blood is redirected to regions of the body that requires instantaneous increased oxygen intake. As such the nervous system signals the blood vessel's vascular smooth muscle to contract, through vasoconstriction so as to raise the blood pressure, when the blood pressure is low.
