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: To control the expression of certain genes according to population density, bacteria use systems of: 
 Options:  <0> Strict response <1> Two components <2> Perception of the quorum. <3> Densitometric adaptation. <4> Negative activation
biology

Question: One of the main concepts of Acceptance and Commitment Therapy is: 
 Options:  <0> The relativization of the context. <1> The underlying reason. <2> The experiential avoidance. <3> The resistance to change. <4> Emotional vulnerability
psychology

Question: The most reactive oxygen radical species and, therefore, most dangerous is: 
 Options:  <0> Superoxide anion <1> Hydrogen peroxide. <2> Ion superoxide <3> Radical hydroxyl. <4> It depends on the tissue.

pharmacology