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: Acetylsalicylic acid is a compound whose pKa is 3.5. What percentage of a dose of this product can be absorbed in the stomach fasting (pH 1.5)? 
 Options:  <1> Less than 10% <2> Between 10% and 20%. <3> More than 90% <4> Between 20% and 40%. <5> 50%
[EX A]: 3

[EX Q]: Question: Pseudomonas aeruginosa is: 
 Options:  <1> Able to ferment a large variety of sugars. <2> Often resistant to many antibiotics for medical use. <3> Responsible for toxi-alimentary infections. <4> Part of the normal microbiota of the skin. <5> A commensal bacterium of the digestive tract.
[EX A]: 2

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