The cyclic alkene shown is treated with ozone and then $\mathrm{Zn}$/$\mathrm{H}{}_2\mathrm{O}$. Which structure is the single product?

The compound shown is 1-methylcyclohexene. Cleaving the ring double bond opens the ring: the methyl-bearing carbon becomes a ketone and the other carbon an aldehyde, giving 6-oxoheptanal. Reductive work-up keeps the aldehyde, so the keto-acid is wrong, and no carbon is lost, so hexanedial is wrong.