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: The immersion oil used for microscopic observation: 
 Options:  <0> Protects the sample from the oxidizing effect of air. <1> Lubricate the objective lens. <2> Reduces refraction and increases resolution. <3> It acts as a lens that increases magnification. <4> Avoid dehydration of the preparation.

A: biology
****
Q: Question: Orally administered proton pump inhibitor drugs: 
 Options:  <0> Neutralize hydrochloric acid from gastric secretion. <1> They dye the stools black. <2> They block the histaminergic receptor. <3> They block the gastrin receptor. <4> They require enteric cover.

A: medicine
****
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.

A:
chemistry
****