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': 'Deep vein thombosis occurs most commonly after ? \nSelect and explain. \nA. Total hip replacement, B. Gastrectomy, C. Prostatic operation, D. Brain surgery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans is \'a\' ie Total hip replacement The factors which result in increased risk of venous thrombosis include advancing age and greater complexity of surgical treatment. Ohopaedic operations on the lower limbs (hip and knee replacements) are especially likely to result in venous thrombosis." - Bailey & Love', 'role': 'assistant'}]