A 17-Year-Old Male Develops Septic Arthritis in His Left Knee

A 17-year-old male develops septic arthritis in his left knee. His physician aspirates synovial fluid and sends it to the microbiology laboratory. A direct Gram stain of the fluid is demonstrated in the image provided.
Source: CDC/Joe Millar
Which of the following tests is necessary for definitive identification of this
Organism?

A) coagulase test.
B) streptococcal serotyping.
C) rapid carbohydrate fermentation test.
D) spot indole test.