Number of optical isomers \(=2^{n}\)

where, \(n=\) number of asymmetric carbon atoms

\(2^{1}=2\)

Number of geometrical isomers \(=2^{n}\) where, \(n=\) number of double bonds \(=2^{1}=2\)

Hence, total number of stereoisomers = Total optical isomers \(4 -\) Total geometrical isomers

\(=2+2=4\)