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: Pathology
[{'content': 'A pathologist examines a renal biopsy from a 45 year old man with nephrotic syndrome and requested a congo red stain to confirm the nature of an amorphous acidophillic extracellular hyalin substances localized within the mesengial matrix of the glomeruli A positive test confirms the presence of \nSelect and explain. \nA. α 1 - antitrypsin, B. Amyloid, C. Copper, D. Glycogen', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The answer is B. A positive congo red test confirms the presence of amyloid. Apple green birefringence is abserved under polarized light.', 'role': 'assistant'}]