Definition: 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 main function of chemokines is: 
 Options:  <1> Regulate lymphocyte traffic. <2> Stimulate cell proliferation in response to chemical agents. <3> Amplify the production of antiviral cytokines. <4> Regulate the selection in the thymus. <5> Antagonize some cytokines.
