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: Pathology
[{'content': 'By definition, granulomas are composed of: \nSelect and explain. \nA. Cholesterol clefts, B. Collagen, C. Endothelial cells and fibroblasts, D. Epithelioid cells', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Granulomatous inflammation is characterized by the presence of granulomas, which by definition are aggregates of activated macrophages (epithelioid cells).', 'role': 'assistant'}]