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: Pharmacology
[{'content': 'Ketotifen is a: \nSelect and explain. \nA. Leucotriene antagonist, B. Antibody against IgE, C. Mast cell stabilizer, D. Mucolytic & expectorant', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ketotifen and sodium cromoglycate prevent degranulation of mast cell.', 'role': 'assistant'}]