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: Statins are used to reduce cholesterol levels and act as analogs of the transition state of an enzyme involved in its biosynthesis. What enzyme is it? 
 Options:  <1> 14-Alpha-demethylase. <2> Hydroxymethylglutaryl coenzyme A (HMGCoA) reductase. <3> Cyclooxygenase 2 (COX-2). <4> Squalene epoxidase. <5> Aromatase
[A]: 2


[Q]: Question: In general, allosteric enzymes: 
 Options:  <1> They link the effectors in the active center. <2> They form covalent bonds with their negative effectors. <3> They originate hyperbolic curves of speed before the concentration of substrate. <4> They change their conformation when they link effectors. <5> They are irreversibly modified when they are inhibited.
[A]: 4


[Q]: Question: The minimum amount of auditory stimulation needed to begin to identify the lyrics of a song is a threshold: 
 Options:  <1> Absolute. <2> Subliminal. <3> Differential. <4> Relative. <5> Musical.
[A]:
1