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'.
Q: Question: The virion of retroviruses:
Options: <1> It has helical shape. <2> It has an icosahedral form. <3> It contains a single copy of its genome. <4> It contains two copies of its genome. <5> It contains a segmented genome.
A:
4