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': 'Time of application for cold pulp testing: \nSelect and explain. \nA. 5 second, B. 10 second, C. 15 second, D. 20 second.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]