This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
[{'content': "Perl's stain is used to demonstrate \nSelect and explain. \nA. Melanin, B. Haemosiderin, C. Bilirubin, D. Lipofuscin", 'role': 'user'}, {'content': "Answer: B \nExplanation: (B) Haemosiderin > Hemosiderosis: With progressive accumulation of hemosiderin, parenchymal cells throughout the body (principally in the liver, pancreas, heart, & endocrine organs) become pigmented, iron can be visualized in tissues by the Prussian blue histochemical reaction, in which colorless potassium ferrocyanide is converted by iron to blue-black ferric ferrocyanide.> Perl's Prussian Blue Stain for Iron-Positive Cells (e.g., activated macrophages) (a.k.a. Perl's acid ferrocyanide reaction)", 'role': 'assistant'}]