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': 'Which of the following is a pure histological landmark for termination of cleaning and shaping of root canal? \nSelect and explain. \nA. CDJ, B. CEJ, C. DEJ, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Cementodentinal junction is considered as a pure histological landmark for termination of cleaning/shaping and obturation.', 'role': 'assistant'}]