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: Indicate the correct answer regarding the pancreas: 
 Options:  <0> Your alpha cells secrete insulin. <1> Its F cells produce somatostatin, which accelerates the secretion of glucagon. <2> Your alpha cells secrete glucagon, which increases the concentration of blood glucose. <3> It is an exclusively endocrine gland. <4> Its delta cells secrete pancreatic polypeptide.
nursery

Question: The bile produced by the liver is stored in the gallbladder from where it is secreted into the duodenum when the muscles involved receive this order in the form of hormonal and nervous signals mediated by: 
 Options:  <0> Colecitocinin and beta-adrenergic sympathetic activation. <1> Pancreozimine and beta-adrenergic sympathetic activation. <2> Secretin and parasympathetic activation. <3> Cholecystokinin and parasympathetic activation. <4> Secretin and alphaadrenergic sympathetic activation.

pharmacology