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: Surgery
[{'content': 'A 40-year old male presents with history of vomiting of blood 2 hours ago. The volume of vomitus was estimated to be 500 ml. His BP was 90/58 mm Hg and pulse was 110/min. On abdominal examination, the spleen was palpable 5 cm below the costal margin. The most likely cause of the bleeding is \nSelect and explain. \nA. Poal hypeension, B. Gastric ulcer, C. Duodenal ulcer, D. Drug-induced mucosal erosion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. Poal hypeension', 'role': 'assistant'}]