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': 'The property of rubber dam that it controls moisture and retracts the soft tissue, best explained in \nSelect and explain. \nA. Access and Visibility., B. Improved properties of dental materials., C. Protection of the patient and operator., D. Operating efficiency.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]