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': 'In tight contacts, the best rubber dam material type is: \nSelect and explain. \nA. Thin, B. Medium, C. Heavy, D. Extra Heavy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The thinner material has the advantage of passing through the contacts easier, which is particularly helpful when contacts are tight.', 'role': 'assistant'}]