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
Confirmatory tests for C. diphtheriae ? 
Select and explain. 
A. Serological tests, B. Isolation in selective media, C. Tests for toxin, D. All
B: Isolation in selective media
Answer: B: Isolation in selective media 
Explanation: Ans. is 'b' i.e., Isolation in selective media . Best diagnosis of diphtheria is made by isolation and culture on selective media.