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: Esters can be obtained from carboxylic acids and alcohols, by applying the Fischer esterification reaction in which: 
 Options:  <1> A base is used as a catalyst. <2> A ketone is used as the solvent. <3> A reducing reagent is used. <4> An oxidizing agent is used. <5> Acid catalysis is used.

A: 5
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Q: Question: What is the approach proposed by the relationship model between therapist and client as expert to expert ?: 
 Options:  <1> The behavioral model. <2> The constructivist perspective <3> The psychoanalysis. <4> The strategic school. <5> The therapy centered on the client.

A: 2
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Q: Question: Indicate the amino acid that, under physiological conditions, has an uncharged side chain: 
 Options:  <1> Arginine <2> Aspartic acid. <3> Glutamic acid. <4> Lysine <5> Threonine

A:
5
****