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
Bacteriophage was discovered by: 
Select and explain. 
A. Robert Koch, B. Twort and d'herelle, C. Menkin, D. Metchinkoff
B: Twort and d'herelle
Answer: B: Twort and d'herelle 
Explanation: None