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
Streptococcus and pneumococcus are differentiated by , all except 
Select and explain. 
A. Bile salt solubility, B. Growth charcteristic, C. Gram staining, D. Inulin fermentation
C: Gram staining
Answer: C: Gram staining 
Explanation: None