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 heart of randomized control trial (RCT) \nSelect and explain. \nA. Protocol, B. Follow-up, C. Assessment, D. Randomization', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]