Q: 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'.
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.
A:
5