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
The following micro - organism constitutes the normal flora of oral cavity - 
Select and explain. 
A. Esch. coli, B. Staphylococcus epidermidis, C. Branhamella catarrhalis, D. Picornavirus
C: Branhamella catarrhalis
Answer: C: Branhamella catarrhalis 
Explanation: None