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: 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
[A]: biology


[Q]: Question: The goblet cells belong to the tissue: 
 Options:  <0> Epithelial. <1> Conjunctive. <2> Cartilaginous. <3> Osseous. <4> Adipose.
[A]: biology


[Q]: Question: Point out the correct answer regarding B lymphocytes. 
 Options:  <0> Its two main subpopulations are called B-helper and B-cytotoxic. <1> They are the cells responsible for the production of antibodies in the rejection of an autologous transplant of hematopoietic progenitors. <2> They are the target cells of the anti-CD20 monoclonal antibody (rituximab). <3> They require co-stimulation CD20-CD19 for the expression of the CD3 molecule on its surface. <4> It is the type of majority lymphocyte in the peripheral blood of patients with Bruton's disease.
[A]:
medicine