This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'All of the following are categorized as secondary lymphoid organs except \nSelect and explain. \nA. Lymph nodes, B. Spleen, C. Thymus, D. Subepithelial collec ons of lymphocytes', 'role': 'user'}, {'content': 'Answer: C \nExplanation: .', 'role': 'assistant'}]