Detailed Instructions: 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: The eudismic index is a parameter with pharmacological interest that expresses the relationship between: 
 Options:  <0> Two diastereomer drugs. <1> Two bioisostero drugs. <2> Two enantiomers <3> A drug and a prodrug, structural analog. <4> Two structural modifications, one hydrophilic and one lipophilic, of a certain drug.
Solution:
pharmacology