Even if you know no chemistry at all, the diagram itself gives you a hint. If the answer is either A or D you have two answers that if you actually do this that are too close to call. Chromatography is not a very precise procedure.
However you should not give that as your reason for answering. The answer is B because the ink that represents B is hardest to dislodge from the solvent. That's because likes dissolve best in likes. So the energy needed to climb that height is provided by the two traveling together. Two means solvent in ink.The other inks all break away much sooner because The solvent / ink complex cannot stay together and move at the same time.
