Optical activity requires a chiral molecule (no plane of symmetry) that rotates plane-polarized light. A molecule is chiral if it lacks an internal plane of symmetry and is not superimposable on its mirror image.

Analyzing the structures:

• The first structure has a plane of symmetry and is achiral (meso compound).
• The second structure is chiral and will show optical activity.
• The third structure has a plane of symmetry and is achiral.
• The fourth structure has a plane of symmetry and is achiral.

Final Answer: The second compound (option 2) will show optical activity.