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 simultaneous expression of IgM and IgD is observed for the first time in lymphocytes: 
 Options:  <1> Early Pro-B. <2> B mature. <3> Late Pro-B. <4> Pre-B. <5> B immature
