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
Who described that P. intermedia is responsible for pregnancy gingivitis? 
Select and explain. 
A. Loesche, B. Kornman, C. Both, D. None
C: Both
Answer: C: Both 
Explanation: 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.