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
Elek's gel precipitation test is for - 
Select and explain. 
A. Gonococcus, B. Diphtheria, C. H. influenza, D. Anthrax
B: Diphtheria
Answer: B: Diphtheria 
Explanation: Ans. is 'b' i.e., Diphtheria