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
Corynebacterium diphtheriae can be grown within 6-8 hours on: 
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: On Loeffler’s serum slope, C. diphtheriae grows after 4–6 hours at 37°C producing small, circular, and white opaque colonies. 
If no colonies are seen, the medium is reincubated further for 24 hours.

Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:218