Which statements about Jones reagent ($\mathrm{CrO}{}_3$/$\mathrm{H}{}_2\mathrm{SO}{}_4$/acetone) are correct?

Jones reagent takes secondary alcohols to ketones, primary alcohols to carboxylic acids, and leaves tertiary alcohols alone, so (A), (B) and (C) are correct. Pentan-3-ol gives pentan-3-one, not an acid (there is no C-C cleavage under these conditions), so (D) is wrong.