This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histo Pathology, Subject name: Pathology
Which of the following is homogenously pink staining extracellular fibrillar protein on congo red staining? 
Select and explain. 
A. Elastin, B. Amyloid, C. Collagen, D. Actin
B: Amyloid
Answer: B: Amyloid 
Explanation: Ans. is 'b' i.e., Amyloid * Congo red is most specific and most commonly used stain stain used for amyloidosis. Appearance of amyloid (fibrillary" 'extracellular protein) are:-a) Congo red stain on light microscopy: Pink or red color to tissue deposits.b) Congo red stain on polarized microscopy: Apple green birefringence.