Hydrocarbon $\mathrm{A}, \mathrm{C}_{10} \mathrm{H}_{14}$, has a UV absorption at $\lambda_{\max }=236 \mathrm{~nm}$ and gives hydrocarbon $\mathrm{B}, \mathrm{C}_{10} \mathrm{H}_{18}$, on catalytic hydrogenation. Ozonolysis of A followed by zinc/acetic acid treatment yields the following diketo dialdehyde:
(a) Propose two possible structures for $\mathrm{A}$.
(b) Hydrocarbon A reacts with maleic anhydride to yield a Diels-Alder adduct. Which of your structures for $\mathrm{A}$ is correct?
(c) Write the reactions, showing starting material and products.