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: For the analysis of traces of inorganic constituents, in samples of organic nature, a preliminary treatment of the sample is needed, which normally consists of: 
 Options:  <0> Dissolve the sample in cold water. <1> Dissolve the sample in hot water. <2> Dissolve the sample between 30 and 70 ºC. <3> Heat the sample between 400 and 700 ºC. <4> Heat the sample in 0.1 M hydrochloric acid.
[EX A]: chemistry

[EX Q]: Question: The eggs are operculated: 
 Options:  <0> Hymenolepis nana. <1> Trichinella spiralis. <2> Enterobius vermicularis. <3> Fasciola hepatica. <4> Ascaris lumbricoides.
[EX A]: biology

[EX Q]: Question: In contrast to the bacterial ones, the eukaryotic chromosomes need multiple origins of replication because: 
 Options:  <0> They can not be replicated bidirectionally. <1> They are not usually circular. <2> The processivity of eukaryotic DNA polymerase is much lower than that of bacterial DNA polymerase. <3> Its replication rate is much slower, and they would need too much time using a single source. <4> They have several DNA polymerases for different purposes, and they need the corresponding variety of origins.
[EX A]:
chemistry