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 proposed by 
Select and explain. 
A. Louis Pasteur, B. Robert koch, C. Paul Ehrlich, D. Joseph lister
A: Louis Pasteur
Answer: A: Louis Pasteur 
Explanation: Louis Pasteur proposed :

Principle of fermentation
Pasteurization of milk
Sterilization techniques
Germ theory of disease.