**Core Concept:** Glomus tumors are rare benign tumors that originate from smooth muscle cells found in the dermal arterioles (glomus bodies) and are commonly known as "mole neuromas" or "acral mucocutaneous junction tumors."

**Why the Correct Answer is Right:** Glomus tumors predominantly occur in the distal extremities, particularly the fingers, toes, and nails, due to the rich vascular supply and high concentration of glomus bodies in these regions. In this case, the correct answer is "A" as it represents the most common site of glomus tumors, which is the fingertips and toes.

**Why Each Wrong Option is Incorrect:**

A. Although glomus tumors can occur in the head and neck region, the correct answer is not "B" as glomus tumors are not as common in this area compared to the distal extremities.

C. Glomus tumors are not primarily found in the liver, spleen, or kidney, so options C and D are incorrect.

**Clinical Pearl / High-Yield Fact:** Glomus tumors can present with symptoms like pain, burning sensation, and cold sensitivity due to their anatomical location and influence on sensory nerves. Recognizing these symptoms and the tumor's location can help in diagnosing glomus tumors and narrowing down the differential diagnoses, as they may resemble other conditions like digital ischemia, Raynaud's phenomenon, or neurovascular injuries.

**Correct Answer:** A. fingertips and toes