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: Anatomy
All of the following are catagorised as secondary lymphoid organs except : 
Select and explain. 
A. Lymph nodes, B. Spleen, C. Thymus, D. Subepithelial collections of lymphocytes
C: Thymus
Answer: C: Thymus 
Explanation: C. i.e. ThymusLymphoid organs are the areas of lymphocytic proliferation. These are the sites which are liable to infection or in possible route to spread of infection