Final answer:
The reflex control of total cardiac output and total peripheral resistance is mainly controlled by sympathetic stimulation of the heart, arterioles, and veins. This sympathetic influence is directed from the cardiovascular centers in the medulla oblongata, affecting heart rate and vascular resistance.
Step-by-step explanation:
The reflex control of total cardiac output and total peripheral resistance is primarily under the control of the sympathetic nervous system. This system influences both the heart rate and vascular tone. The medulla oblongata contains the cardiovascular center which orchestrates the balance of sympathetic and parasympathetic inputs, adjusting cardiac output and peripheral resistance accordingly. Sympathetic stimulation increases heart rate through the cardiac accelerator nerves and constricts blood vessels via vasomotor nerves, thereby increasing blood pressure. Parasympathetic stimulation, predominantly via the vagus nerve, serves to reduce heart rate but has insignificant effects on systemic blood vessels.
Based on the mechanisms described, the correct answer to the student's question is: a. sympathetic stimulation of the heart, arterioles, and veins. This is because the parasympathetic system has little to no effect on the peripheral resistance and the somatic system is not involved in autonomic control. Additionally, autonomic control of the heart only without including arterioles and veins does not fully describe the reflex control of total cardiac output and total peripheral resistance.