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': 'Secondary retention for a removable partial denture is provided by \nSelect and explain. \nA. The indirect retainer, B. The direct retainer, C. Intimate contact between the denture bases and the underlying tissues, D. Direct and indirect retainers', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]