A stimulus is a change in an organism's surrounding that causes it to react.
Answer:
C. altering blood volume
Explanation:
Systemic blood pressure has a number of controls, both nervous and hormonal in nature. Nerve control is said to be short term and is basically done by the sympathetic and parasympathetic autonomic nervous system which, as a balance, seeks to balance systemic blood pressure to values considered stable.
This type of control works through chemoreceptors, reflex arcs associated with vasomotor fibers, and reflex arcs involving baroreceptors. The goal of short-term pressure control is to maintain balance.
