Rf values varying with solvent polarity

[ashtonjam]

TBR Organic Chem, Section 8 Lab techniques, Passage 7 (#43):

43. A spot that shows an Rf value of 0.72 in a nonpolar
solvent like hexane will likely show what Rf value in a
polar solvent like ethyl acetate?
A. 1.84
B. 0.72
C. 0.13
D. -0.21

Answer: C

I've always been taught in class and organic synthesis lab that polar solvents will tend to make everything on a column run faster, nonpolar and polar compounds alike. The reasoning behind this is that (on a silica gel column) the polar solvent will interact with the silica gel and take up all the 'sites' so that the compounds have no choice but to quickly elute.

TBR reasoning is the opposite:

An Rf value of 0.72 implies that the compound is highly soluble in the solvent and that the compound has a very low affinity for the surface of the TLC plate. A change in solvent from nonpolar to polar would show a reduction in solubility, and thus a reduction in the Rf value.

Can someone clear this up, and can both trains of thought be correct, or must one be wrong?

I also searched and found a thread with a similar type of problem here:
http://forums.studentdoctor.net/showthread.php?t=959883

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[tdod]

For starters, none of the other options are possible (eliminate .72 b/c if you change the solvent you will change the rF).


I think that both ideas could be correct if the speed-increase for the polar solvent is greater than the speed-increase for the non-polar solute.