**Core Concept**
The patient's symptoms suggest a diagnosis of colorectal cancer, specifically a rectosigmoid carcinoma, given the location of the symptoms (early morning bloody diarrhea, change in bowel habits, intermittent obstruction, feeling of incomplete evacuation, and tenesmus).

**Why the Correct Answer is Right**
The treatment of choice for rectosigmoid carcinoma, especially in a patient without a positive family history for carcinoma, is surgical resection of the tumor. The goal of surgery is to remove the tumor and affected portion of the colon or rectum, followed by restoration of intestinal continuity. The type of surgery depends on the tumor's location, size, and stage. In this case, a low anterior resection (LAR) or an abdominoperineal resection (APR) may be performed, depending on the extent of the tumor.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because chemotherapy and radiation therapy are not the primary treatments for rectosigmoid carcinoma, especially in early stages. While they may be used as adjuvant therapies to reduce the risk of recurrence, they are not the first line of treatment.
**Option B:** This option is incorrect because medical management with medications such as laxatives, antispasmodics, or anti-diarrheal agents is not effective in treating rectosigmoid carcinoma. These symptoms are a result of the tumor's presence, not a primary gastrointestinal disorder.
**Option C:** This option is incorrect because endoscopic resection or polypectomy is not suitable for rectosigmoid carcinoma, especially if it has invaded the muscularis propria or has lymph node involvement. These procedures are typically used for early-stage colon cancer or polyps.

**Clinical Pearl / High-Yield Fact**
The key to diagnosing rectosigmoid carcinoma is to recognize the classic symptoms: early morning bloody diarrhea, change in bowel habits, intermittent obstruction, feeling of incomplete evacuation, and tenesmus. These symptoms often occur in older adults and should prompt a thorough evaluation, including colonoscopy and biopsy.

**Correct Answer:** C. Surgical resection of the tumor is the treatment of choice for rectosigmoid carcinoma.