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.

[EX Q]: Question: The number of Barr corpuscles of the cells of a man with karyotype 48, XXXY is:
Options: <0> two. <1> one. <2> 0 <3> 3. <4> Four.
[EX A]: biology

[EX Q]: Question: The 2,4-diaminopteridine systems, such as aminopterin or methotrexate, are good antitumor agents since they reduce the biosynthesis of purines and pyrimidines by inhibiting the enzyme:
Options: <0> Timidylate synthetase <1> Aromatase <2> Topoisomerase <3> Reverse transcriptase <4> Dihydrofolate reductase.
[EX A]: pharmacology

[EX Q]: Question: Glucagon increases the activity of:
Options: <0> Protein kinase A. <1> Acetyl-CoA carboxylase. <2> Pyruvate kinase. <3> Glycogen synthase. <4> Fosfofructoquinasa-1.
[EX A]:
chemistry