The correct answer is (a) 0 Diopter.
A diopter is a unit of measurement for the power of a lens. The power of a lens is the reciprocal of its focal length in meters. A lens with a focal length of 1 meter has a power of 1 diopter. A lens with a focal length of 0.5 meters has a power of 2 diopters. A lens with a focal length of 0.25 meters has a power of 4 diopters.
Sun glasses are typically plano lenses, which have a power of 0 diopters. Plano lenses do not change the way light bends, and they do not correct any vision problems. They are used to protect the eyes from the sun’s harmful UV rays.
Option (b), 1 diopter, is incorrect because sun glasses typically have a power of 0 diopters.
Option (c), 2 diopters, is incorrect because sun glasses typically have a power of 0 diopters.
Option (d), 4 diopters, is incorrect because sun glasses typically have a power of 0 diopters.