Which of the following do not show geometrical isomerism?
As we know in geometrical isomerism,
Geometrical isomerism is possible only when each of the doubly bonded carbon atom has two different groups (see the examples above). Thus, compounds of the following type will not show geometrical isomerism.
Note the similar atoms (groups) on one or both of the carbon atoms.
Now take a look at option (b), It has H as both substituents on one carbon.
Therefore it will not show geometrical isomerism.