Final answer:
Light quality can be reduced due to reflection and refraction, with interference and dispersion affecting intensity and color respectively. Refraction, influenced by the index of refraction varying with wavelength, can disperse light into colors when passing through a prism.
Step-by-step explanation:
The main factor that reduces light quality can be influenced by various elements which can include wavelength, intensity, reflection, or refraction. However, among the options provided, reflection and refraction are more directly related to changes in light quality through interactions with materials. When light reflects from surfaces, especially multiple surfaces as seen in thin films, it can interfere with itself leading to changes in intensity and color—a phenomenon known as interference. Refraction, on the other hand, occurs when light changes direction and speed upon entering a different medium; this can alter the perceived color and sharpness of an image. For instance, light entering a prism is dispersed into its constituent colors because the index of refraction varies with wavelength, bending different colors at different angles.