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
True about diptheria is - 
Select and explain. 
A. Loffler's serum is highly selective medium for C. diptheria, B. Elek's Gel is a precipitation test, C. Metachromatic granules is produced on stain only by one strain of C. diphtheria, D. Gm -ve bacilli, non motile, non capsulated
B: Elek's Gel is a precipitation test
Answer: B: Elek's Gel is a precipitation test 
Explanation: None