Instructions: 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'.
Input: Question: The proofreading activity of DNA Polymerase: 
 Options:  <1> It is a 5'-3'exonuclease activity. <2> It is a 3'-5'exonuclease activity. <3> It is a 5'-3'polymerizing activity. <4> It is an endonuclease activity. <5> It is a transesterification activity.
Output:
2