Optical isomerism is a type of stereoisomerism in which compounds have the same molecular formula and connectivity but differ in the arrangement of their atoms in space, resulting in non-superimposable mirror images. In order to exhibit optical isomerism, a molecule must have a chiral center, which is a carbon atom bonded to four different groups.

Let's analyze each option to determine which one exhibits optical isomerism.

a) Butanol-1:
Butanol-1, also known as 1-butanol or n-butanol, has the molecular formula C4H10O. However, it does not have a chiral center. The carbon atom bonded to the hydroxyl group is also bonded to three hydrogen atoms and a methyl group, which are all different. However, due to the presence of a plane of symmetry, the molecule is achiral and does not exhibit optical isomerism.

b) Butanol-2:
Butanol-2, also known as 2-butanol or sec-butanol, has the same molecular formula C4H10O as butanol-1. However, it does have a chiral center. The carbon atom bonded to the hydroxyl group is also bonded to two hydrogen atoms, a methyl group, and an ethyl group, which are all different. This molecule lacks a plane of symmetry and therefore exhibits optical isomerism. The two possible optical isomers of butanol-2 are (R)-2-butanol and (S)-2-butanol.

c) Butene-1:
Butene-1, also known as 1-butene, has the molecular formula C4H8. It does not have a chiral center as it contains a double bond between two carbon atoms. Therefore, it cannot exhibit optical isomerism.

d) Butene-2:
Butene-2, also known as 2-butene, has the same molecular formula C4H8 as butene-1. Similarly, it does not have a chiral center due to the presence of a double bond. Hence, it does not exhibit optical isomerism.

Therefore, the correct answer is option b) Butanol-2, which exhibits optical isomerism due to the presence of a chiral center.

Butanol 2 have chiral carbon atom so it show optical isomerism