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': 'The commonest cause for lymphedema of upper limb is - \nSelect and explain. \nA. Filariasis, B. Congenital, C. Neck surgery, D. Post mastectomy irradiation', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Filariasis", 'role': 'assistant'}]