This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitreous and retina, Subject name: Ophthalmology
The most common organism causing chorioretinitis in HIV is 
Select and explain. 
A. CMV retinitis, B. Toxoplasma chorioretinitis, C. Syphilitic retinitis, D. Pneumocystis carini
A: CMV retinitis
Answer: A: CMV retinitis 
Explanation: (Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 470 - 472)Cytomegalovirus (CMV) is the most common cause of chorioretinitis in patients who are HIV positive