Hey there! Hello!
One popular example of paper chromatography in action is when you have a strip of paper with a line of black ink on it with the tip of the paper dipped in a solvent, not touching the actual black ink line. The solvent will travel up the paper and separate the inks into different colors, since the black ink is made up of different colors of ink to produce a very dark color. You can look up videos of paper chromatography labs to see what I'm talking about.
Based on this example, the answer to your problem is probably A, separate different molecules from one another. This method can also be used with other things besides ink to separate the particles and see what something's made of.
Hope this helped you out! :-)