Correct Response: B. The curvature of the surface of a lens causes parallel light rays to bend towards a focal point. This bending is the result of the difference between the index of refraction of the lens material and that of air. This bending phenomenon is called refraction. Dispersion (A) is the separating of a ray of light into different colors, often by a prism. This is not a basic function of binocular lenses. While some light reflects (C) off of the surface of the lens, this is not its basic function.
Diffraction (D) is a phenomenon that occurs when light passes through one or more narrow slits. This not related to the basic function of binocular lenses.
