Definition: 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'.
Input: Question: In ion exchange chromatography, the carboxylic acid functional group is used as: 
 Options:  <1> As a strong anion exchanger in ion exchange resins. <2> As a strong cation exchanger in ion exchange resins. <3> As a weak anion exchanger in ion exchange resins. <4> As a weak cation exchanger in ion exchange resins. <5> It is never used in ion exchange.
