Hydrocarbon A, C10H14 absorbs 4 equiv. of hydrogen to give B, C10H22 when hydrogenated over a Pd/C catalyst. Treatment of A with aqueous H2SO4 and Hg(II) gives a single ketone, C, C10H16O. Oxidation of A with KMnO4 gives CO2 and the keto carboxylic acid D shown below. Propose a structure for A.