You will be given a definition of a task first, then some input of the task.
In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.

Question: Sulfasalazine is used for the treatment of ulcerative colitis. It is a prodrug of 5-aminosalicylic acid that is activated by a process of:
Options: <1> Hydrolysis of an ester. <2> Hydrolysis of an amide. <3> Oxidative dealkylation. <4> Reducing rupture of the azoderivative. <5> Aromatic hydroxylation.
Output:
4