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
Crystal violet blood agar is used for which bacteria? 
Select and explain. 
A. Corynebacterium diphtheriae, B. Staph aureus, C. b-hemolytic streptococcus, D. Meningococcus
C: b-hemolytic streptococcus
Answer: C: b-hemolytic streptococcus 
Explanation: b-hemolytic streptococcus