Colon cancer affects the ________________.

Colon cancer specifically affects the large intestine. The large intestine, also known as the colon, is the final part of the digestive system and plays a crucial role in processing waste and absorbing water and nutrients. Cancer can develop in any part of the colon or rectum, but the term "colon cancer" generally refers to malignant growths in the large intestine.

Understanding the anatomy helps clarify why the other options do not apply. For instance, the stomach is responsible for digestion and does not contain colon tissue; therefore, it cannot be affected by colon cancer. Similarly, the small intestine, which is involved in digestion and nutrient absorption, is distinct from the large intestine. The gallbladder, which stores bile produced by the liver, is also not connected to the large intestine and thus is unrelated to colon cancer. Therefore, the correct association of colon cancer with the large intestine is fundamentally accurate based on the anatomical and physiological context of the disease.