**Core Concept**
Right-sided colon carcinoma typically presents with non-specific and less dramatic symptoms compared to left-sided colon cancer. This is due to the larger diameter of the right colon and its relatively slower transit time, allowing more time for the development of complications. The right colon's primary function is to absorb water and electrolytes, which may lead to different presenting features.

**Why the Correct Answer is Right**
Right-sided colon carcinoma often presents with weight loss, iron-deficiency anemia due to chronic blood loss, and abdominal pain. The decreased transit time in the left colon typically leads to symptoms like obstruction, altered bowel habit, and melena in left-sided colon cancer. In contrast, right-sided colon cancer may present with anemia (III), as the blood loss is often occult and not immediately apparent.

**Why Each Wrong Option is Incorrect**
* **Option A:** Obstruction (I) is more commonly associated with left-sided colon cancer due to the narrower diameter of the left colon and its faster transit time.
* **Option B:** Altered bowel habit (II) is a non-specific symptom and can be associated with both left and right-sided colon cancer, but is more typical of left-sided lesions.
* **Option C:** Melena (IV) is more commonly associated with upper gastrointestinal bleeding or left-sided colon cancer, as the blood is more likely to be altered by the time it reaches the right colon.

**Clinical Pearl / High-Yield Fact**
Remember that right-sided colon cancer often presents with non-specific symptoms, and a high index of suspicion is necessary for early diagnosis. A key red flag is iron-deficiency anemia without a clear source, which warrants further investigation.

**Correct Answer:** C. Anemia.