Which of the following statements about the normal line is true?

The normal line is critical in understanding how light interacts with surfaces. When light strikes a surface, the normal line is established at the point where the incident ray meets the surface. This line is drawn at a 90-degree angle to the surface and acts as a reference for measuring angles of incidence and reflection.

This geometry is essential because it allows us to apply the laws of reflection, which indicate that the angle of incidence is equal to the angle of reflection, both of which are measured with respect to the normal line. By defining the normal line this way, we can accurately analyze how light behaves when it encounters different materials.

Other statements, while related to light and reflection, do not accurately describe the characteristics of the normal line.