Correct Answer – A
If we rotate the second compound out of the plane of paper by `180^(@)` (clockwise or counterclockwise), we notice that the two are nonsuperposable mirror images. Compounds in `(2)` and `(3)` are not enantomers as their molecules posses a plane of symmetry (i.e. of plane perpendicular to the paper and containing both `CH_(3)` and `OH`, the plane theat passers between the two Br atoms). In `(4)`, the second compound becomes identical to the first one if we rotate it (out of the plane paper) by `180^(@)` (clockwise or counterclockwise).