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': 'Factor responsible for pregnancy gingivitis is: \nSelect and explain. \nA. Hormonal imbalance, B. Micro-organism associated with plaque, C. Poor oral hygiene, D. Drugs', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]