**Core Concept**
Carotid body tumors are benign neoplasms arising from the paraganglia of the carotid body, a chemoreceptor organ located at the bifurcation of the common carotid artery. These tumors are typically slow-growing and can cause symptoms due to compression of nearby structures, such as the carotid artery, jugular vein, and vagus nerve.

**Why the Correct Answer is Right**
The best treatment option for carotid body tumors is surgical excision. This involves carefully removing the tumor while preserving the surrounding nerves and vascular structures. The goal of surgery is to completely excise the tumor, thereby preventing recurrence and minimizing the risk of complications. The carotid body tumor's anatomical location near the bifurcation of the common carotid artery necessitates a meticulous surgical approach to avoid damaging the nearby carotid sinus baroreceptors, which play a crucial role in regulating blood pressure.

**Why Each Wrong Option is Incorrect**
**Option B:** Radiotherapy is not the primary treatment for carotid body tumors as these tumors are benign and do not typically exhibit malignant behavior.

**Option C:** Chemotherapy is not indicated for carotid body tumors as they are not responsive to systemic therapy and are best managed with surgical excision.

**Option D:** Carotid artery ligation, both proximal and distal to the tumor, is not a recommended treatment for carotid body tumors. This approach may lead to complications such as stroke, hypoglossal nerve palsy, and glottic edema due to the tumor's proximity to vital structures.

**Clinical Pearl / High-Yield Fact**
It is essential to note that carotid body tumors are often asymptomatic until they reach a significant size, at which point they may cause symptoms such as neck mass, hoarseness, and difficulty swallowing. Early detection and surgical excision are crucial to prevent complications and ensure a favorable outcome.

**✓ Correct Answer: A. Excision of tumor**