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 child come with fever, cold, cough, membrane over tonsils; nasal swab is taken, culture should be done on which medium for earliest diagnosis ? 
Select and explain. 
A. Loffelers serum slop, B. L. J. media, C. MC Conkey's Agar, D. Citrate media
A: Loffelers serum slop
Answer: A: Loffelers serum slop 
Explanation: Ans. is 'a' i.e., Loffelers serum slop Diphtheria bacilli grow on Loeffler's serum slope very rapidly and colonies can be seen in 6-8 hours, long before other bacteria grow.