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: What element plays a physiological role in the prevention of gastroesophageal reflux? 
 Options:  <0> Upper esophageal sphincter <1> Angle of His. <2> Hernia of Hiato. <3> Purkinje angle. <4> Pyloric sphincter
[A]: pharmacology


[Q]: Question: The reaction conditions for the preparation of 2-methyl-2-methoxypropan-1-ol from 2,2-dimethyloxirane are: 
 Options:  <0> Methanol in acid medium. <1> Lithium aluminum hydride in methanol. <2> Methylmagnesium bromide and subsequent hydrolysis. <3> Sodium methoxide in methanol. <4> Triphenylphosphine in methanol.
[A]: chemistry


[Q]: Question: Polarography is an analytical technique that refers to: 
 Options:  <0> The absorption of electromagnetic radiation. <1> The emission of electromagnetic radiation. <2> The voltametry with mercury electrode. <3> The use of palladium as a reference electrode. <4> To the potential of asymmetry.
[A]:
chemistry