This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Culture medium for Corynebacterium diphtheria is 
Select and explain. 
A. Loeffler's serum slope, B. McConkey's agar, C. Sabourauds agar, D. Lowenstein Jensen medium
A: Loeffler's serum slope
Answer: A: Loeffler's serum slope 
Explanation: Loeffler's serum slope: diphtheria bacilli grow on this media very rapidly and colonies can be seen in 6-8 hours, long before other bacteria grow. Colonies are the first small, circular white opaque disc but enlarge on continued incubation and may acquire a distinctly yellow tint. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 242