Thermoregulation via vasodilation

Steps:

• Exercise raises body temperature by increasing metabolic heat production.
• To cool down, the body promotes heat loss through the skin.
• Vasodilation widens skin blood vessels, increasing blood flow to the surface.
• This allows more heat to radiate and convect away from the body.

Why D is correct:

• Dilation of blood vessels follows the physiological law of thermoregulation, where increased skin perfusion enhances radiative and convective heat loss to lower core temperature.

Why the others are wrong:

• A: Fat layer insulates and retains heat, worsening overheating.
• B: Shivering is a heat-generating response triggered by cold, not cooling.
• C: Positive feedback amplifies changes (e.g., in labor), not stabilizes temperature.

Final answer: D