Question

A ray of light passing through the ________ retraces its path.

Answer 1

1. A ray of light passing through the center of curvature of a spherical mirror retraces its path (gets reflected along the same path).
2. As the ray of light passes through the center of curvature of a mirror it strikes the mirror along the normal i.e. it incidences onto the mirror at 90 degrees.

Hence, a ray of light passing through the centre of curvature retraces its path.