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: Determines the isotype change of the immunoglobulin heavy chain: 
 Options:  <1> The receptor of cell B. <2> The CD40 molecule and the cytokines. <3> IgM or IgD of the lymphocyte membrane. <4> Age. <5> The location of the lymphocyte within the germinal center.
