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: Social & Preventive Medicine
[{'content': 'Which of the following vectors has a habit of frequent vomiting? \nSelect and explain. \nA. Sand flea, B. House fly, C. Mite, D. Mosquito', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Housefly has a habit of frequent vomiting. The regurgitated stomach contents or "vomit drop" is a source of infection. Chapter: Environment and health Ref: Park 21st edition page: 715.', 'role': 'assistant'}]