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
Which of these pathologies is the most common benign tumour of the parotid gland? 
Select and explain. 
A. Mumps, B. TB, C. Heerfordt syndrome, D. Pleomorphic adenoma
D: Pleomorphic adenoma
Answer: D: Pleomorphic adenoma 
Explanation: Mumps causes the classic bilateral parotitis, but it can present as a unilateral enlargement in rare cases. Heerfordt syndrome includes sarcoidosis.
Tuberculosis historically was associated with ‘cold abscess’. It is caused by Mycobacterium tuberculosis, an acid-fast bacterium that does not stain with Gram stain. It requires Ziehl–Neelsen staining.