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
[{'content': 'An infant had high grade fever and respiratory distress at the time of presentation to the emergency room. The sample collected for blood culture was subsequently positive showing growth of ααααα -hemolytic colonies. On Gram staining these were gram positive cocci. In the screening test for identification, the suspected pathogen is likely to be susceptible to the following agent : \nSelect and explain. \nA. Bacitracin, B. Novobiocin, C. Optochin, D. Oxacillin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]