This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amyloidosis, Subject name: Pathology
On electron microscopy amyloid characteristically exhibits: 
Select and explain. 
A. B-plated sheets, B. Hyaline globules, C. 7.5-10 nm fibrils, D. 20-25 nm fibrils
C: 7.5-10 nm fibrils
Answer: C: 7.5-10 nm fibrils 
Explanation: Propeies of Amyloid Proteins: -Physical Nature of Amyloid: Electron microscopy-- Continuous, non-branching fibrils with a diameter of approximately 7.5 to 10 nm. X-ray crystallography and infrared spectroscopy-- Cross-b-pleated sheet conformation. This conformation is responsible for the distinctive Congo red staining and birefringence of amyloid. -Chemical Nature of Amyloid The AL (amyloid light chain)-excess of the light chains will deposit outside the cell in the form of Amyloid protein.It is seen in Multiple Myeloma patients. The AA (amyloid-associated) type of amyloid fibril protein is derived from unique non-Ig protein made by the liver. b-amyloid protein (Ab)-Seen in Alzheimer disease.(deposition of Ab plaque in the brain,causing damage to the coical neurons lowering the acetylcholine levels ,leading to |Memory.