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: Cyclopentadiene is so reactive that leaving it at room temperature slowly dimerizes by a reaction of: 
 Options:  <0> Friedel-Crafts. <1> Diels-Alder. <2> Markovnikov. <3> Suzuki <4> Gabriel.
[EX A]: chemistry

[EX Q]: Question: The following may occur in multimeric form associated with the J chain: 
 Options:  <0> IgA and IgG. <1> IgD and IgM, <2> IdE and IgD. <3> IgA and IgD. <4> IgA and IgM.
[EX A]: biology

[EX Q]: Question: Most Gram-positive bacteria do not grow in MacConkey's medium because it contains: 
 Options:  <0> Bile salts and crystal violet. <1> Lactose and casein hydrolyzate. <2> Neutral red <3> Mannitol <4> Basic fuchsin
[EX A]:
biology