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
All of the following lab tests can be used to distinguish Streptococcus mutans from other oral streptococci, except 
Select and explain. 
A. Gram staining, B. Fermentation of mannitol and sorbital, C. Production of intracellular and extracellular adherent polysaccharide, D. Colony morphology on saliva agar
A: Gram staining
Answer: A: Gram staining 
Explanation: None