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
A 12 year old child presents with fever and cervical lymphadenopathy. Oral examination shows a grey membrane on the right tonsil extending to the anterior pillar. Which of the following medium will be ideal for the culture of the throat swab for rapid identification of the pathogen? 
Select and explain. 
A. Nutrient agar, B. Blood agar, C. Loeffler’s serum slope, D. LJ medium
C: Loeffler’s serum slope
Answer: C: Loeffler’s serum slope 
Explanation: The symptoms of the given case are suggestive of C. diphtheria infection.

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