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': 'In polycythaemia vera the most common postoperative complication following major surgery is? \nSelect and explain. \nA. Thrombosis, B. Gastric ulcer, C. Diabetes insipidus, D. Haemorrhage', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Thrombosis", 'role': 'assistant'}]