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: What enzyme does a retrovirus use to synthesize DNA copy of its genome? 
 Options:  <1> DNA polymerase I. <2> cDNA polymerase I. <3> RNA polymerase I. <4> cDNA polymerase II. <5> Reverse transcriptase
