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: Medicine
[{'content': 'Renal involvement in multiple myeloma is characterized by \nSelect and explain. \nA. Nitrogen retention, B. Hypertension, C. Edema, D. Haematuria', 'role': 'user'}, {'content': 'Answer: A \nExplanation: It is due to the accumulation of light chain immunoglobulins, which here\xa0can be referred by nitrogen retention.', 'role': 'assistant'}]