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'.

[EX Q]: 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
[EX A]: 5

[EX Q]: Question: The transmembrane proteins that bind to intracellular and extracellular proteins are: 
 Options:  <1> Ocludines. <2> Cadherins. <3> Actins. <4> Integrins <5> Desmocolinas.
[EX A]: 4

[EX Q]: Question: Histidine is characterized by: 
 Options:  <1> Present an indole group in its structure. <2> Present a unique N in its structure. <3> A side chain of aromatic character. <4> A side chain that can take or release protons at physiological pH. <5> Being a protein involved in inflammation.
[EX A]:
4