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
[{'content': 'All of the following are catagorised as secondary lymphoid organs except : \nSelect and explain. \nA. Lymph nodes, B. Spleen, C. Thymus, D. Subepithelial collections of lymphocytes', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 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', 'role': 'assistant'}]