Which combining form is used for the study of the stomach?

The combining form used for the study of the stomach is "Gastr/o." This term is derived from the Greek word "gaster," which means stomach. It is commonly used in medical terminology related to the stomach and its studies, such as in the term "gastroenterology," which is the branch of medicine focused on the digestive system as a whole, particularly the stomach and intestines.

In contrast, "Hepat/o" refers to the liver, which is critical for various metabolic processes and detoxification in the body. "Lapar/o" relates to the abdominal wall, often used in the context of surgical procedures performed through the abdominal wall. Lastly, "Esophag/o" pertains specifically to the esophagus, the tube that connects the throat to the stomach, and is not directly related to studies of the stomach itself. Therefore, "Gastr/o" is the most appropriate choice when discussing the study of the stomach.