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: Proton pump inhibitor drugs are useful in the treatment of: 
 Options:  <0> Constipation. <1> Corneal ulcer. <2> Peptic ulcer. <3> Traveler's diarrhea. <4> Crohn's disease.
[A]: nursery


[Q]: Question: A potential receiver: 
 Options:  <0> It is produced by the opening of voltage-dependent channels. <1> Increase its frequency if the intensity of the stimulus increases. <2> It occurs after the binding of the neurotransmitter to the postsynaptic receptor. <3> They occur if the trigger threshold is exceeded. <4> It can be exciter or inhibitor.
[A]: biology


[Q]: Question: The interaction between the urea cycle and the citric acid cycle is carried out at the level of: 
 Options:  <0> Uric acid. <1> Succinate <2> Ammonia. <3> Urea. <4> Fumarate
[A]:
pharmacology