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: Microbiology
[{'content': 'Legionnaire disease is caused by? \nSelect and explain. \nA. Motile gram positive, B. Motile gram negative, C. Non-motile gram positive, D. Non-motile gram negative', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Motile gram negative . Legionnaire disease is caused by legionella pneumophila, which is a gram-negative motile coccobacilli.", 'role': 'assistant'}]