Which specialty covers the stomach, small intestine, and the bowels down to the rectum?

The specialty that focuses on the stomach, small intestine, and the bowels down to the rectum is gastroenterology. Gastroenterologists are medical professionals who diagnose and treat conditions related to the digestive system, which includes all the organs involved in processing food, digestion, and waste elimination.

Gastroenterology encompasses a wide range of disorders such as ulcers, inflammatory bowel disease, irritable bowel syndrome, and liver diseases. The expertise in this specialty allows gastroenterologists to provide comprehensive care for patients suffering from digestive issues.

In contrast, endocrinology pertains to the study of hormones and the glands that produce them, focusing mainly on metabolic processes and conditions like diabetes and thyroid disorders. Ophthalmology, on the other hand, is the branch of medicine that deals with the eyes and visual system, thus covering entirely different organ systems unrelated to digestion. The option stating 'none of the above' doesn’t apply here since gastroenterology accurately represents the relevant specialty.