This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory Disorders, Subject name: Ophthalmology
[{'content': 'Most common organism causing chorioretinitis in HIV is- \nSelect and explain. \nA. CMV retinitis, B. Tocoplasma retinochoroiitis, C. Syphilitic retinitis, D. Pneumocystis carini', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., CMV retinitis o "Cytomegalovirus (CMV) is the most common cause of chorioretinitis in patients who are HIV positive.', 'role': 'assistant'}]