instruction:
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: A parameter of great importance in chromatography is the equivalent height of theoretical plate (H). The van Deemter equation describes the behavior of a filler column for gas-liquid chromatography, where H = A + (B / u) + Cu, so that: 
 Options:  <0> C is the parameter that is taken as a measure of the quality of the filling of the column. <1> A is the coefficient that collects the contribution of longitudinal diffusion. <2> B is the parameter that is related to the resistance to the transfer of matter that opposes the stationary phase. <3> u is the linear velocity of the mobile phase. <4> B is canceled in columns without filling.
answer:
chemistry


question:
Question: The set of means and systems that facilitate the contact of the infectious agent with the recipient subject corresponds to: 
 Options:  <0> Source of infection. <1> Habitat. <2> Transmission mechanism. <3> Biotope <4> Reservoir.
answer:
nursery


question:
Question: Inhibits gastrin secretion: 
 Options:  <0> Parasympathetic stimulation. <1> Sight, aroma and taste of the food. <2> Stomach distension <3> Presence of proteins in the stomach. <4> Somatostatin.
answer:

biology