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
Earliest growth of diphtheria is detect on which media ? 
Select and explain. 
A. Potassium tellurite media with iron, B. McConkey's agar, C. Dorset egg medium, D. Loeffler's serum slope
D: Loeffler's serum slope
Answer: D: Loeffler's serum slope 
Explanation: Ans. is 'd' i.e., Loeffler's serum slope Diphtheria bacilli grow on Loeffler's serum slope very rapidly and colonies can be seen in 6-8 hours, long before other bacteria grow.