Correct option is 3
Let us examine the given molecules for chiral centres
Alkenes are planar molecules.
They have a horizontal plane (plane of the paper) bisecting it in two similar halves (up and below)
Hence is not chiral and will not show optical isomerism.
This molecule also has a horizontal plane bisecting it in two halves and thus is not chiral.
Hence it will not show optical isomerism.
The molecule has four different groups tetrahedrally attached to it.
No symmetrical elements are present and also the carbon centre is chiral.
The mirror images are also not superimposable on each other.
Hence, it will show optical isomerism.
The given molecule has four groups attached to it tetrahedrally.
This molecule has a vertical plane of symmetry bisecting it in two halves and thus is not chiral.
Hence, it will not show optical isomerism.
