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: Dental
[{'content': 'Which of the following is absent in normal pulp \nSelect and explain. \nA. Mast cells, B. Antigen presenting cells, C. T lymphocytes, D. Macrophages', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]