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
Toxigenicity of C. diphtheria is determined by- 
Select and explain. 
A. Elek's gel ppt test, B. Aselole's reaction, C. Nagler's reaction, D. All
A: Elek's gel ppt test
Answer: A: Elek's gel ppt test 
Explanation: Ans. is 'a' i.e., Elek's gel ppt test