This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'Repeat upper GI endoscopy in a patient with a gastric ulcer is performed after how many weeks of PPI therapy to assess the healing of the ulcer and confirm absence of malignancy: \nSelect and explain. \nA. 2 weeks, B. 4 weeks, C. 6 weeks, D. 12 weeks', 'role': 'user'}, {'content': "Answer: C \nExplanation: Repeat upper endoscopy is done in patients with a gastric ulcer after 6 to 10 weeks of acid suppressive therapy to confirm healing of the ulcer and absence of malignancy. 2% to 4% of repeat upper endoscopies have been repoed to disclose gastric cancer. Ref: Sleisenger and Fordtran's, E-9, P-305", 'role': 'assistant'}]