Concept:Cis–trans isomerism is a type of stereoisomerism caused by restricted rotation around a bond.Explanation:Cis and trans isomers have the same molecular formula and the same bond connectivity.They differ only in the spatial arrangement of atoms or groups around a rigid bond, such as a double bond.This restricted rotation prevents the groups from interconverting freely.Therefore, this form of isomerism is called geometrical isomerism.Answer:B. geometrical