Well, if you can't experiment safely, why experiment at all? I believe it's D because of that.
Explanation:
K in chromatography is defined as a partition coefficient. It is an equilibrium constant that determines the measure to which the solutes partition between two phases.
K = Cm/Cs
where Cm is solute concentration in mobile phase
Cs is solute concentration in stationary phase
When K is more, then it implies that the solute concentration in the mobile phase is more in chromatography test.
PE = mgh, g= 9.8 m/s^2
10 kg * 9.8 m/s^2 * 300 m
= 29400 J