Step 1: What is aspirin.
Aspirin is a common medicine used to reduce pain and fever. We need its proper chemical name.
Step 2: How aspirin is made.
Aspirin is made from salicylic acid by adding an acetyl group to its $\text{OH}$ group. This change is called acetylation.
Step 3: Name the product.
After adding the acetyl group, the compound is called acetylsalicylic acid. This is the chemical name of aspirin.
Step 4: Rule out methyl salicylate.
Methyl salicylate is oil of wintergreen, a different compound used in balms. It is not aspirin.
Step 5: Rule out the others.
Salicylic acid is the starting material, not aspirin itself. Ethyl salicylate is yet another ester, not aspirin.
Step 6: Final choice.
So the chemical name of aspirin is acetylsalicylic acid.\[ \boxed{\text{Acetylsalicylic acid}} \]