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.
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Question: Question: When comparing the characteristics of pragmatic or confirmatory clinical studies with explanatory or exploratory clinical studies, which of the following is an advantage of the former? 
 Options:  <0> Information about subgroups of patients representative of the usual clinical practice. <1> Very homogeneous sample, with little variability. <2> Greater capacity to detect differences in the effectiveness of interventions. <3> Greater internal validity <4> Smaller sample size

Answer: medicine


Question: Question: Why is the presence of lentigo in older people? 
 Options:  <0> Cell dehydration <1> Small hemorrhages due to capillary fragility. <2> Hyperplasia of intraepidermal melanocytes. <3> Deficiency of collagen and elastin. <4> Lipofuscin deposits.

Answer: nursery


Question: Question: The determination of cyanide by the Liebig method is based on the addition of a silver nitrate standard solution: 
 Options:  <0> Until complete precipitation of silver cyanide. <1> Until the precipitation of silver cyanide begins. <2> Until the appearance of a red precipitate of silver chromate. <3> Until the AgCN complex is quantitatively formed. <4> Until the precipitation of silver iodide, yellow.

Answer:
chemistry