This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
[{'content': 'In a patient of orbital cellulitis, microorganism on culture show greenish colonies and optochin sensitivity. The most likely organism is: \nSelect and explain. \nA. Strep, viridans, B. Staphylococcus, C. Pseudomonas, D. Pneumococcus', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., PneumococcusGram-positive cocci which form a-hemolytic colonies (Greenish colonies) and is optochin sensitive is pneumococcus.The characteristic features of pneumococcus are: (BIO) (Memory Aid)(a) Bile solubility.(b) Optochin sensitivity.(c) Inulin fermentation.(d) Shows quellung reaction (capsular delineation).(e) Forms draughtsman or carrom coin colonies (Colonies with central umbonation).", 'role': 'assistant'}]