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: Azidothymidine (AZT) used against the human immunodeficiency virus:
Options: <1> It binds to the cellular RNA polymerase and blocks transcription. <2> It binds to the early promoter of the virus and prevents its recognition by RNA polymerase. <3> Antagonizes the phosphorylation of nucleosides, thus inhibiting the synthesis of viral DNA. <4> Blocks the transport of thymidine to the cellular interior. <5> Inhibits transcriptase
A:
5