The diagram below illustrates the pathway of blood flow through mammalian skin under different environmental temperatures.
Which of the options, A to D, correctly describes the physiological response coordinated by the hypothalamus when an endotherm experiences an increase in environmental temperature?
Vasodilation of shunt vessels to allow more blood to bypass the superficial capillaries.
Relaxation of erector pili muscles, reducing the insulating layer of trapped air next to the skin.
Decreased sympathetic stimulation of sweat glands to maximize evaporative cooling.
Constriction of superficial arterioles to increase heat loss by radiation.