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': 'Periodontitis may best be described as \nSelect and explain. \nA. A chronic inflammatory disease with periods of remission and exacerbation, B. A chronic inflammatory disease that usually does not manifest itself clinically before the age of 40, C. A degenerative disease of the periodontium, D. An acute inflammatory disease of long duration', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]