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': "Langerhan's cells are absent in \nSelect and explain. \nA. Junctional epithelium, B. Sulcular epithelium, C. Oral epithelium, D. All of the above", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]