In this task, you are given a question and answer options for that question. Using this information, you have to classify each text into different topics: medicine, nursery, psychology, chemistry, pharmacology, biology.

[EX Q]: Question: The standard free energy of activation of a reaction is: 
 Options:  <0> The difference in free energy between the basal state of the products and the substrates. <1> The difference of the enthalpy minus the entropy of the system. <2> The basal energy of the substrates in a catalyzed reaction. <3> The additional free energy that molecules must reach to reach the state of transition. <4> The energy released from a catalysed reaction.
[EX A]: chemistry

[EX Q]: Question: The minimum amount of auditory stimulation needed to begin to identify the lyrics of a song is a threshold: 
 Options:  <0> Absolute. <1> Subliminal. <2> Differential. <3> Relative. <4> Musical.
[EX A]: psychology

[EX Q]: Question: Grapefruit juice is: 
 Options:  <0> A potent enzyme inducer of cytochrome P450 (CYP3A4). <1> A potent enzyme inhibitor of cytochrome P450 (CYP3A4). <2> A promoter of the absorption of drugs administered orally. <3> An advisable food to increase the bioavailability of drugs of acidic nature. <4> A food without consequence in the kinetics of disposal of drugs eliminated by metabolism in which cytochrome P450 is involved.
[EX A]:
pharmacology