Task: Question Answering
Input (English): 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.
Output (English): 5