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: When centrifuging human peripheral blood in a density gradient in Ficoll: 
 Options:  <1> The mononuclear cells float on the Ficoll. <2> The lymphocytes remain in the background. <3> The erythrocytes float on the Ficoll. <4> The granulocytes float on the Ficoll. <5> The monocytes remain in the background.
