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': 'Manual mulling is carried out for not more than \nSelect and explain. \nA. 1-2 seconds, B. 2-4 seconds, C. 1-4 seconds, D. 2-5 seconds', 'role': 'user'}, {'content': 'Answer: D \nExplanation: In mulling, the mixture is enveloped in a dry piece of rubber dam and vigorously rubbed between the first finger and thumb. This process should not exceed 2-5 seconds.\nReference: Marzouk Operative dentistry, pg-113', 'role': 'assistant'}]