This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'The best investigation for the diagnosis of amyloidosis is \nSelect and explain. \nA. Colonoscopy, B. Rectal biopsy, C. Upper GI endoscopy, D. CT scan', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Diagnosis Microscopic examination - biopsies from kidney, gingiva, rectum Congo red staining on abdominal fat aspirates Serum & urine protein electrophoresis Bone marrow aspiration - to r/o plasmacytosis Scintigraphy with radiolabelled serum amyloid P (SAP) component', 'role': 'assistant'}]