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
By definition, granulomas are composed of: 
Select and explain. 
A. Cholesterol clefts, B. Collagen, C. Endothelial cells and fibroblasts, D. Epithelioid cells
D: Epithelioid cells
Answer: D: Epithelioid cells 
Explanation: Granulomatous inflammation is characterized by the presence of granulomas, which by definition are aggregates of activated macrophages (epithelioid cells).