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
Most common cause of unilateral parotid swelling in a 27 yr old male is - 
Select and explain. 
A. Warthins tumor, B. Pleomorphic adenoma, C. Adenocarcinoma, D. Haemangioma
B: Pleomorphic adenoma
Answer: B: Pleomorphic adenoma 
Explanation: None