**Core Concept**
Shunt vessels are a type of blood vessel that allows blood to bypass the capillary bed and directly return to the venous system. They play a crucial role in regulating blood flow and temperature in the body.

**Why the Correct Answer is Right**
Shunt vessels, particularly arteriovenous anastomoses, are found in the skin and are involved in thermoregulation. When the body temperature rises, shunt vessels dilate, allowing more blood to flow directly from the arteries to the veins, thereby releasing heat. Conversely, when the body temperature drops, shunt vessels constrict, reducing blood flow and heat loss. This process helps maintain a stable body temperature.

**Why Each Wrong Option is Incorrect**
**Option A:** Shunt vessels are not evenly distributed throughout the skin; they are primarily found in areas such as the face, ears, and hands, where thermoregulation is crucial.
**Option B:** Shunt vessels do not play a significant role in nutrition. Their primary function is to regulate blood flow and temperature, not to facilitate exchange of oxygen and nutrients with the tissues.
**Option D:** Shunt vessels are indeed regulated by the autonomic nervous system, specifically through the sympathetic nervous system, which controls their dilation and constriction in response to changes in body temperature.

**Clinical Pearl / High-Yield Fact**
Shunt vessels are a key factor in the pathophysiology of conditions such as Raynaud's disease, where abnormal constriction of shunt vessels leads to reduced blood flow and tissue ischemia.

**✓ Correct Answer: C. Play a role in thermoregulation**