Q: 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'.
Question: Which of the following statements regarding the double-stranded DNA molecule is true?
Options: <1> All the hydroxyl groups of the pentoses participate in the bonds. <2> The bases are perpendicular to the axis. <3> Each chain is identical. <4> Each chain is parallel. <5> Each chain replicates itself.
A:
2