You are presented with the quiz "What may be caused by an infection or injury of the lungs?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "pneumonia may be caused by an infection or injury of the lungs" and "legionnaires' disease is a type of pneumonia". 

So, what's the best answer to the question?


 

   Legionnaires' disease        