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.
--------
Question: Question: Which of these species is a free radical? 
 Options:  <0> The molecule NO. <1> The O2 molecule. <2> The N2O molecule. <3> The OH- anion. <4> The ClO- anion.

Answer: chemistry


Question: Question: In an electrochemical cell, the supporting electrolyte serves to: 
 Options:  <0> That the principle of electroneutrality in the dissolution is fulfilled. <1> That their ions are electrolized preferably in order to prevent the consumption of electroactive substance. <2> That in the cell there is transport by migration, in order to achieve greater sensitivity. <3> That the solution has an adequate electrical conductivity. <4> Encourage transport by diffusion of the electroactive substance.

Answer: chemistry


Question: Question: Which of the following chemicals is considered the most lethal individual carcinogen? 
 Options:  <0> Alcohol. <1> Smoke of the tabacco. <2> Tar. <3> Benzene. <4> Nickel.

Answer:
nursery