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': "An 80 year old asymptomatic woman was detected to have a monoclonal spike on serum electrophoresis (IgG levels 1.5 g/dl). 1: one marrow revealed plasma cells of 8%. The most likely diagnosis is - \nSelect and explain. \nA. Multiple myeloma, B. Indolent myeloma, C. Monoclonal gammopathy of unknown significance, D. Waldenstorrn's macroglobulinemia", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]