**Core Concept**
Rectal cancer is a type of malignant neoplasm that arises from the epithelial cells lining the rectum, which is a part of the large intestine. The pathogenesis of rectal cancer involves genetic mutations, epigenetic alterations, and environmental factors, leading to uncontrolled cell growth and tumor formation.

**Why the Correct Answer is Right**
The correct answer is related to the staging of rectal cancer. Rectal cancer is typically staged using the TNM system, which takes into account the size and extent of the primary tumor (T), the presence or absence of lymph node metastasis (N), and the presence or absence of distant metastasis (M). The correct answer is likely related to the importance of accurate staging in determining the prognosis and treatment plan for rectal cancer patients.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a true statement about rectal cancer. Rectal cancer is a type of adenocarcinoma, which arises from the glandular epithelium of the rectum.
**Option B:** This option is incorrect because it is not a true statement about rectal cancer. While radiation therapy is often used in the treatment of rectal cancer, it is not the primary treatment modality.
**Option C:** This option is incorrect because it is not a true statement about rectal cancer. While surgery is often used to treat rectal cancer, it is not the only treatment option available.

**Clinical Pearl / High-Yield Fact**
It is essential to accurately stage rectal cancer using the TNM system to determine the prognosis and treatment plan. The correct staging can significantly impact patient outcomes and guide treatment decisions.

**Correct Answer:** C.