What characteristic of the planet is directly related to the depth of the light decrease observed during a transit?

Answer

The size of the planet relative to the size of its star.

The fraction of light blocked, or the depth of the dip, scales directly with the ratio between the planet's area and the star's area.

What characteristic of the planet is directly related to the depth of the light decrease observed during a transit?
measurementastronomyexoplanetsdetection