Which of the following molecule shows cis-trans isomers?

Explanation

For cis-trans isomerism, the rotation must be restricted in the molecule (so, cannot occur in compounds that only have C-C single bonds) and there must be two non-identical groups on each double-bonded carbon atom. Option A does not fulfill this requirement, as each double-bonded carbon atom has two identical groups i.e. each C has two H atoms attached to it.Option B does not fulfill these requirements as it is a halogenoalkane, with no C-C double bonds so, rotation is not restricted in the molecule.Option C fulfills these requirements, as not only is rotation restricted as it has a C-C double bond, each carbon atom has two non-identical atoms, i.e. each C has one Hydrogen atom and one Bromine atom so, this option is correct.Option D does not fulfill the requirements as well as even though one double-bonded carbon atom has two non-identical atoms i.e. one H atom and one Cl atom, the other carbon has two identical Cl atoms.