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: Medicine
Commonest lesion in middle mediastinum is 
Select and explain. 
A. Lipoma, B. Aneurysm, C. Congenital cyst, D. Germ cell tumour
C: Congenital cyst
Answer: C: Congenital cyst 
Explanation: None