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 organism is increased in pregnant ladies \nSelect and explain. \nA. Porphyromonas intermedius, B. Porphyromonas gingivalis, C. Porphyromonas melaninogenicus, D. Eichenella corrodens', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]