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: About free radicals: 
 Options:  <0> They are compounds that contain two or three unpaired electrons in an outer orbital. <1> Reactive oxygen species (ROS) in the cell are only generated enzymatically. <2> Hydrogen peroxide is the most damaging radical in the cell. <3> The hydroxyl radical originates non-enzymatically (Heber-Weiss reaction) and damages proteins and DNA. <4> Oxygen is a triradical.
[EX A]: chemistry

[EX Q]: Question: In suppression ion chromatography: 
 Options:  <0> A single column is used and the conductivity of the mobile phase is kept very low. <1> The eluent must be able to be removed selectively after separation and prior to the conductometric measurement. <2> The eluent incorporates a regenerating solution of strong acid flowing in the same direction as the mobile phase. <3> Weak exchangers are used from polystyrene polymers. <4> A mobile phase with ionic conductivity gradient is used.
[EX A]: chemistry

[EX Q]: Question: Type III hypersensitivity reactions are characterized by: 
 Options:  <0> The activation of mast cells. <1> The deposit of immunocomplexes. <2> The activation of macrophages. <3> Appearance of a neutrophil infiltrate. <4> Cytotoxicity reactions.
[EX A]:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
pharmacology

