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.

Question: Which of these species is a free radical?
Options: <0> The molecule NO. <1> The O2 molecule. <2> The N2O molecule. <3> The OH- anion. <4> The ClO- anion.
chemistry

Question: Which of the following correlates with retinopathy of the premature newborn?
Options: <0> The bilirubin. <1> Gentamicin <2> The corticoids <3> The Oxigen. <4> Fentanyl
medicine

Question: When centrifuging human peripheral blood in a density gradient in Ficoll:
Options: <0> The mononuclear cells float on the Ficoll. <1> The lymphocytes remain in the background. <2> The erythrocytes float on the Ficoll. <3> The granulocytes float on the Ficoll. <4> The monocytes remain in the background.
biology