Geometrical isomerism is possible in case of

The configurational isomerism occurring due to the different arrangement of groups(or) atoms around double bonded atoms or a ring is called geometrical isomerismand compounds are called geometrical isomers.In  option (1)  CH3−C≡C−CH3 option (2) CH3−CH2−CH=CH2  and option (3)  CH3−CH=CH2 Arrangements of atoms (or) groups similar around double bond.In option (4)   groups around carbon carbon double bond are different and it show geometrical isomerism.