Bella is fascinated with optical fibers: flexible, coated strands of glass or other material that use total internal reflection to channel light. If light enters one end of an optical fiber at an angle, the light can be totally internally reflected when it strikes the edge of the fiber along its length. After successive reflections, the light emerges from the other end. Bella has done some reading on the subject and has learned that optical fibers can transmit light efficiently over long distances and bend light around corners or obstacles. The core of the optical fiber is often surrounded by a cladding, a material that has a lower index of refraction than the core, to improve efficiency. A large critical angle is needed to maximize efficiency, because a large c will mean fewer reflections along the optical fiber and, therefore, a faster travel time. Bella shares her knowledge about optical fibers with Asante, then challenges him to consider an engineering problem: A manufacturer designs an optical fiber with an index of refraction of 1.56. There are three choices of cladding material, designated A, B, and C, with indices of refraction nA = 1.46, nB = 1.48, and nC = 1.50