90. The students used salicylic acid and acetic anhydride to synthesize aspirin in the experiment of “The Preparation of Aspirin”. The chemical reaction is shown as below: Which compound will react with FeCl3 to become a purple complex? (A) Salicylic acid (B) Acetic anhydride (C) Aspirin (D) Acetic acid (E) 18 M sulfuric acid