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': 'Acid mucin is best demonstrated by the stain - \nSelect and explain. \nA. Alcian blue, B. Periodic Acid Schiff (P.A.S.), C. Van Gieson, D. Reticulin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mucin is produced by epithelial cells of mucous membrane & mucous glands, as well as by some connective tissues\nStains for mucin\n\nMucicarmine\nAlcian blue.\n\nNote :-\xa0Epithelial cell mucin stains positively with periodic acid-Schiff (PAS), while connective tissue mucin does not.', 'role': 'assistant'}]