Optical isomerism occurs when a molecule has a chiral center (carbon with four different substituents) and lacks a plane of symmetry. The compound must be non-superimposable on its mirror image.

Analyzing the given structures (images not renderable here):

Only compounds with a chiral carbon show optical activity. Look for a carbon atom bonded to four distinct groups. Compounds with such a carbon and no internal symmetry are optically active.

Final Answer: The compounds that show optical isomerism are those with a chiral center and no plane of symmetry.