An unknown hydrocarbon A with the formula C7H14 reacts with 1 molar equivalent of H2 over a palladium catalyst to give hydrocarbon B. Hydrocarbon A also reacts with OsO4 to give diol C. Treatment of diol C with periodic acid gives ketone D and aldehyde E. When oxidized with KMnO4 in acidic solution, A gives two fragments. One fragment is propionic acid, CH3CH2CO2H, and the other fragment is ketone D. Draw the structure of compound D.