Which of the following structures permits cis-trans isomerism ?

• Geometric isomerism is shown by  carbon structures (also called cis-trans isomerism) when there is unsaturation present  and two different group between carbon then they show geometrical isomerism carbon molecules having different structures but same molecular formula. In cis same mass group are on same side in trans same groups are opposite to each other.

          Cis and Trans isomerism is permitted in XYC = CXZ

$$\begin{gathered} {}_{\mathrm{y}⋰}{}^{\mathrm{x}\ddots }\mathrm{C}={\mathrm{C}}_{\ddots \mathrm{z} }^{⋰\mathrm{x}}\mathrm{Cis} \\ {}_{\mathrm{y}⋰}{}^{\mathrm{x}\ddots }\mathrm{C} = {\mathrm{C}}_{\ddots \mathrm{x}}^{⋰\mathrm{z}} \mathrm{Trans} \end{gathered}$$