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: In a cohort study, the number of new cases of disease per person per unit of time is: 
 Options:  <0> The annual incidence. <1> The cumulative incidence or probability. <2> The prevalence rate <3> The density or incidence rate. <4> The relative risk of developing the disease.
[A]: medicine


[Q]: Question: The Pearson correlation coefficient: 
 Options:  <0> It is always greater than 1. <1> It is always less than 1. <2> It is between 0 and 1. <3> It is between -1 and 0. <4> It is between -1 and 1.
[A]: chemistry


[Q]: Question: If an analytical method allows to determine 1 ppm of Pb, we are referring to: 
 Options:  <0> 1 mg / L. <1> 1 mg / mL. <2> 1 μg / L. <3> 1 ng / L. <4> 1 ng / mL.
[A]:
chemistry