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
A patient presents with signs of pneumonia. The bacterium obtained from sputum was a Gram positive cocci which showed alpha hemolysis on sheep agar. Which of the following test will help to confirm the diagnosis ? 
Select and explain. 
A. Bile solubility, B. Coagulase test, C. Bacitracin test, D. CAMP test
A: Bile solubility
Answer: A: Bile solubility 
Explanation: None