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
Staphylococcus is 
Select and explain. 
A. Gram - positive cocci, B. Gram - negative cocci, C. Gram - positive bacillus, D. Gram - negative bacillus
A: Gram - positive cocci
Answer: A: Gram - positive cocci 
Explanation: Gram positive bacteria 

There are 6 classic gram-positive bacteria that cause human disease.


Of these 2 are cocci


Staphylococci
Streptococci (including anaerobic peptostreptococci)


Other 4 are bacilli


Corynebacterium
Bacillus
Clostridium
Listeria