This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
[{'content': 'Most common cause of pleural effusion in HIV patients - \nSelect and explain. \nA. Kaposi sarcoma, B. Lymphoma, C. P.carinii, D. Mycobacterium tuberculosis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Pleural effusions are seen in 70% of cases of pulmonary Kaposi sarcoma , a fact that is often helpful in the differential diagnosis. Primary effusion lymphoma (PEL), also referred to as body cavity lymphoma, presents with lymphomatous pleural, pericardial, and/ or peritoneal effusions in the absence of discrete nodal or extranodal masses. (Harrison's Principles of internal medicine, 20 th edition, page 1566)", 'role': 'assistant'}]