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
Which one of the following is aspirin ? 
Select and explain. 
A. Methyl salicylate, B. Para–aminobenzoic acid, C. Para–aminosalicylic acid, D. Acetyl salicylic acid
D: Acetyl salicylic acid
Answer: D: Acetyl salicylic acid 
Explanation: None