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': 'All of these are antigen presenting cells except \nSelect and explain. \nA. Follicular Dendritic Cells, B. Microflod Cells, C. Mast Cells, D. Langerhans Cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]