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
Germ theory of disease was introduced by: March 2013 
Select and explain. 
A. Robe Koch, B. Loeffler, C. Walter Reed, D. John Snow
D: John Snow
Answer: D: John Snow 
Explanation: Ans. D i.e. John Snow Germ theory of disease It refers to the discovery in the late 19th century that some infectious diseases are caused by microorganisms, small organisms too small to see without magnification, that invades the host. The theory supplanted earlier explanations for disease such as miasma theory.