This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histology, Subject name: Anatomy
[{'content': "Hassall's corpuscles are seen in: \nSelect and explain. \nA. Thymus, B. Spleen, C. Lymph node, D. Appendix", 'role': 'user'}, {'content': 'Answer: A \nExplanation: A - D.I Fiores Atlas of histology, p. 130', 'role': 'assistant'}]