Which one of the following compounds can exist as cis-trans isomers?

1. Pent-1-ene (${\text{CH}}_2={\text{CH-CH}}_2{\text{CH}}_2{\text{CH}}_3$) has two identical H atoms on the terminal carbon, so no cis-trans isomerism.2. 2-Methylhex-2-ene (${\text{(CH}}_3{\text{)}}_2{\text{C=CH-CH}}_2{\text{CH}}_2{\text{CH}}_3$) has two identical methyl groups on the same carbon atom of the double bond, so no cis-trans isomerism.3. 1,1-Dimethylcyclopropane has both methyl groups on the same carbon, so no cis-trans isomerism.4. 1,2-Dimethylcyclohexane can have the two methyl groups on the same side (cis) or opposite sides (trans) of the ring plane.