Teacher:In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Teacher: Now, understand the problem? Solve this instance: Question: Which of the following alcohols has the lowest pKa value ?:
Options: <1> Ethanol. <2> 2-Chloroethanol. <3> 2-Propanol. <4> 2,2,2-Trifluoroethanol. <5> 1,1-Dimethylethanol.
Student:
4