This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding from the GUT and diseases of esophagus, Subject name: Medicine
[{'content': 'Which indicates least chances of re-bleeding after hematemesis episodes: \nSelect and explain. \nA. Adherent clot on ulcer, B. Clean based ulcer, C. Gastric ulcer with AV malformation, D. Visible bleeding vessel.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Most patients of hematemesis have a rebleed within the next 3 days of an episode. UGIE is diagnostic as well as prognostic as a clean based ulcer has a least chance of re-bleed while visible bleeding vessel has the highest chances.', 'role': 'assistant'}]