Optical activity occurs when a compound has a chiral center (carbon with four different groups) and lacks a plane of symmetry. A compound is optically active if it is not superimposable on its mirror image.

Analyzing the given structures (images not renderable here):

The first compound has a chiral center and no symmetry, making it optically active.

The second compound is symmetric and achiral (meso compound), so it is optically inactive.

The third compound has a plane of symmetry and is achiral, thus optically inactive.

The fourth compound is symmetric and achiral, so optically inactive.

Final Answer: The first compound is optically active.