TASK DEFINITION: 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.
PROBLEM: Question: Immunoglobulin isotype change affects: 
 Options:  <0> The constant regions of the heavy chains. <1> The constant regions of the light chains. <2> The totality of heavy chains. <3> The entire immunoglobulin molecule. <4> The hypervariable regions of the heavy chains.

SOLUTION: biology

PROBLEM: Question: Osmium oxide (VIII), OsO4: 
 Options:  <0> It is a compound in a state of oxidation very common among transition metals. <1> It is the only binary compound of osmium with oxygen. <2> It has the structure of rhenium trioxide. <3> It is inert compared to alkaline hydroxides. <4> It is used as an oxidant in organic chemistry.

SOLUTION: chemistry

PROBLEM: Question: The Grignard reagents attack the epoxides to give, after the appropriate hydrolysis: 
 Options:  <0> Carboxylic acids. <1> Cyclic amides. <2> Open aliphatic chains. <3> Open-chain alcohols. <4> Cyclic ethers.

SOLUTION:
pharmacology