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
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 a rapid identification of the pathogen 
Select and explain. 
A. Nutrient agar, B. Blood agar, C. Loffler's serum slope, D. Lowenstein Jensen medium
C: Loffler's serum slope
Answer: C: Loffler's serum slope 
Explanation: The symptoms and grey membrane over the right tonsil is suggestive of infection with Corynebacterium diphtheriae. To confirm the diagnosis culture of the throat swab on Loeffler's serum slope or Tellurite blood agar can be done. Loeffler's serum slope: Growth is rapid on Loeffler's serum slope. The colonies can be seen in 6-8 hours, long before other bacteria grow. Colonies are first small, circular white opaque discs 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