Which medical field studies the stomach, intestines, and associated diseases?

Gastroenterology is the medical field that focuses specifically on the study of the stomach, intestines, and the associated diseases that affect these organs. This specialty involves diagnosing and treating a wide range of conditions, including gastrointestinal disorders such as acid reflux, irritable bowel syndrome, Crohn's disease, and various types of infections or cancers that can impact the digestive system.

The other fields mentioned deal with entirely different bodily systems: cardiology focuses on the heart and blood vessels, nephrology is centered around kidney function and diseases, and endocrinology pertains to glands and the hormones they produce. By understanding the specific focus of gastroenterology, it becomes clear why this is the correct choice when identifying the field dedicated to studying the stomach and intestines.