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 what chromatographic mode is the stationary phase formed by solid particles with controlled pore size? : 
 Options:  <1> Chromatography of distribution in normal phase. <2> Distribution chromatography in reverse phase. <3> Ion pair chromatography. <4> Ion exchange chromatography. <5> Chromatography of molecular exclusion or size.
