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: Only one of the following cell types synthesizes interleukin IL-12; which one?: 
 Options:  <1> Cytotoxic T lymphocytes. <2> NK cells. <3> Myeloid dendritic cells. <4> Helper T lymphocytes. <5> Endothelial cells
