Optical isomers are characterized by:

Optical isomers, also known as enantiomers, are specific types of stereoisomers that are non-superimposable mirror images of each other. Their defining characteristic is the ability to rotate plane-polarized light. When a beam of plane-polarized light passes through a solution containing an optical isomer, the plane of polarization is rotated in a specific direction. One enantiomer will rotate the light in a clockwise direction (known as dextrorotatory), while the other will rotate it counterclockwise (known as levorotatory). This property is fundamental to understanding the behavior of chiral molecules in various chemical and biological contexts.

The other options do not accurately represent the key feature of optical isomers. While some optical isomers may have a fixed structural configuration, it is not a defining characteristic of all optical isomers. The presence of identical functional groups is also not a determinant of chirality, as enantiomers can contain multiple identical functional groups but differ in spatial arrangement. Lastly, a uniform arrangement of atomic structure does not apply because optical isomers involve variations in the spatial configuration of the atoms, leading to their unique rotational properties.