This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'Two or more oligoclonal bands in cerebrospinal fluid are most often positive in- \nSelect and explain. \nA. Acute bacterial meningitis, B. Multiple sclerosis, C. Subarachnoid harmorrhage, D. Polyneuropathy', 'role': 'user'}, {'content': "Answer: B \nExplanation: Oligoclonal bands (OCBs) are bands of immunoglobulins that are seen when a patient's blood serum, or cerebrospinal fluid (CSF) is analyzed. They are used in the diagnosis of various neurological and blood diseases, especially in multiple sclerosis. The blood serum can be gained from a clotted blood sample. Ref Davidson 23rd edtion pg 450", 'role': 'assistant'}]