A thin-layer chromatography (TLC) plate coated with silica gel is developed using 90:10 hexane:ethyl acetate as the mobile phase. A mixture contains benzoic acid, benzaldehyde, and ethylbenzene. Which order of increasing Rf values is most consistent with the polarities of these compounds under the stated conditions?
a) benzaldehyde<benzoic acid<ethylbenzene
b) ethylbenzene<benzaldehyde<benzoic acid
c) benzoic acid<benzaldehyde<ethylbenzene
d) benzoic acid<ethylbenzene<benzaldehyde