This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
A child presented with fever and lymphadenopathy. Oral examination shows a grey membrane over right tonsil. Which of the following medium will be used for early diagnosis of pathogen? 
Select and explain. 
A. Nutrient agar, B. Blood agar, C. Loeffler's serum slope, D. Lowenstein Jensen medium
C: Loeffler's serum slope
Answer: C: Loeffler's serum slope 
Explanation: Ans. is 'c' i.e., Loeffler's serum slope(Ref: Ananthanarayan, 9th/e, p. 240 and 8th/e, p. 235-236)Fever, cervical lymphadenopathy and grey membrane on the tonsil extending to anterior pillar is suggestive of diphtherial infection. For rapid growth the specimen is inoculated on Loeffler's serum slope which shows the growth in 6 hours.