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
Legionnaire disease is caused by- 
Select and explain. 
A. Motile gram positive, B. Motile gram negative, C. Non-motile gram positive, D. Non-motile gram negative
B: Motile gram negative
Answer: B: Motile gram negative 
Explanation: None