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': 'Chemically aspirin is \nSelect and explain. \nA. Acetyl salicylic acid, B. Para-aminosalicylic acid, C. Para-aminobenzoic acid, D. Acetaminophen', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Acetyl salicylic acid", 'role': 'assistant'}]