Which of the following alkenes give only carboxylic acid(s) (no ketone and no $\mathrm{CO}{}_2$) when treated with hot concentrated acidified $\mathrm{KMnO}{}_4$?

Hex-3-ene gives two molecules of propanoic acid, and cyclohexene gives hexanedioic acid, so only acids form. 2-Methylbut-2-ene gives propanone together with ethanoic acid, and 1-methylcyclohexene gives 6-oxoheptanoic acid, a keto acid. Each of these contains a ketone group.