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': 'Impression techniques are used for recording \nSelect and explain. \nA. Oral mucosal tissues, B. Dental hard tissues, C. Oral mucosal tissues and dental hard tissues, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]