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': 'Who described that P. intermedia is responsible for pregnancy gingivitis? \nSelect and explain. \nA. Loesche, B. Kornman, C. Both, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Kornman and Loesche reported that the subgingival flora changes to a more anaerobic flora as pregnancy progresses; the only microorganism that increases significantly during pregnancy is P. intermedia.', 'role': 'assistant'}]