**Core Concept**
Squamous cell carcinoma (SCC) of the anus is a rare but aggressive malignancy that requires prompt and effective treatment to prevent local recurrence and metastasis. The treatment of choice for SCC of the anus is a multidisciplinary approach that involves a combination of surgery, chemotherapy, and radiation therapy.

**Why the Correct Answer is Right**
The treatment of choice for SCC of the anus is chemoradiation, which involves the concurrent administration of chemotherapy and radiation therapy. This approach has been shown to improve local control and survival rates in patients with SCC of the anus. The chemoradiation regimen typically consists of a combination of fluorouracil (5-FU) and mitomycin-C (MMC), which are administered concurrently with radiation therapy. The radiation therapy is delivered using a technique called conformal radiation therapy, which allows for precise targeting of the tumor and minimizes damage to surrounding tissues.

**Why Each Wrong Option is Incorrect**
**Option A:** Surgery alone is not sufficient for the treatment of SCC of the anus, as it has a high risk of local recurrence.
**Option B:** Chemotherapy alone is not effective for SCC of the anus, as the tumor is resistant to chemotherapy.
**Option C:** Radiation therapy alone is not sufficient for the treatment of SCC of the anus, as it has a high risk of local recurrence and metastasis.

**Clinical Pearl / High-Yield Fact**
It is essential to note that SCC of the anus is often associated with human papillomavirus (HPV) infection, and patients with a history of HPV infection may be at higher risk of developing SCC of the anus.

**Correct Answer:** C. Chemoradiation.