**Core Concept**
Glomus tumors are rare, benign neoplasms originating from modified smooth muscle cells of the juxtaglomerular apparatus in the kidney. However, the most common location is the glomus body in the dermis of the skin, particularly in the distal extremities.

**Why the Correct Answer is Right**
The most common location for glomus tumors is in the subungual region of the distal fingers and toes. These tumors arise from the glomus body, a specialized arteriovenous anastomosis that plays a key role in thermoregulation. The glomus body is composed of modified smooth muscle cells, endothelial cells, and pericytes.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because glomus tumors are not associated with the adrenal glands, which are involved in the renin-angiotensin system.
**Option B:** Incorrect because glomus tumors are not commonly found in the brain, although they can occur in this location.
**Option C:** Incorrect because glomus tumors are not typically associated with the liver, which is involved in detoxification and metabolism.

**Clinical Pearl / High-Yield Fact**
Glomus tumors are usually benign, but they can cause significant morbidity due to their tendency to bleed easily and cause pain. They are often associated with a blue discoloration of the nail bed, known as a glomus tumor sign.

**Correct Answer: C. Subungual region of the distal fingers and toes.**