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.

[Q]: Question: What is the procedure called instrumental conditioning in which the instrumental response eliminates or prevents the occurrence of an aversive stimulus ?: 
 Options:  <0> Positive reinforcement. <1> Punishment. <2> Negative reinforcement. <3> Omission. <4> Extinction.
[A]: psychology


[Q]: Question: Hyponatremia is part of the clinical picture of: 
 Options:  <0> Addison's disease <1> Central diabetes insipidus. <2> Nephrogenic insipid diabetes. <3> Mellitus diabetes. <4> Febrile states.
[A]: pharmacology


[Q]: Question: Does not block the flow of electrons in oxidative phosphorylation: 
 Options:  <0> Cyanide. <1> Antimycin A. <2> CO. <3> 2,4-DNP. <4> Amital.
[A]:
biology