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
The commonest cause for lymphedema of upper limb is - 
Select and explain. 
A. Filariasis, B. Congenital, C. Neck surgery, D. Post mastectomy irradiation
A: Filariasis
Answer: A: Filariasis 
Explanation: Ans. is 'a' i.e., Filariasis