Task: Question Answering
Input (English): 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 (English): 4