Final answer:
The test performed to visualize the stomach for ulcers, lesions, and malignancies is called endoscopy.
Step-by-step explanation:
The test performed to visualize the stomach for ulcers, lesions, and malignancies is called endoscopy. During an endoscopy, a thin, flexible tube with a camera on the end is inserted through the mouth and into the stomach. This allows the doctor to directly view the stomach lining and identify any abnormalities, such as ulcers or tumors.