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: The Aminoacyl-tRNAs:
Options: <1> They are the precursors of the RANs. <2> They are enzymes that catalyze the synthesis of amino acids. <3> They are part of the ribosomes. <4> They are the tRNAs loaded with the amino acid specified by its anticodon sequence. <5> They are synthesized by RNA Polymerase II.
[EX A]: 4

[EX Q]: Question: Of the following reaction mechanisms, in which there is an inversion of the configuration from the reactant to the product of the reaction ?:
Options: <1> Bimolecular nucleophilic substitution (SN2). <2> Unimolecular elimination (E1). <3> Unimolecular nucleophilic substitution (SN1). <4> Addition Markovnikov. <5> Addition anti-Markovnikov.
[EX A]: 1

[EX Q]: Question: Which of the following analytical determinations is less useful for decision making in the follow-up and control of an HIV-infected person?
Options: <1> CD4 lymphocyte count in peripheral blood. <2> Quantification of immunoglobulin. <3> Measurement of viral load. <4> Studies of HIV resistance to antiretroviral drugs. <5> Analysis of the co-receptor tropism.
[EX A]:
2