AIPMT 2008 Physics and Chemistry Paper

Given compound,
CH3‌CH=CHCH2CHBrCH3
may also be written as follows:
Both geometrical isomerism (cis-trans form) and optical isomerism is possible in this compound.
Number of optical isomer =2n=21=2 (Here n= number of asymmetric carbon)
Therefore, total number of stereoisomers =2+2=4