Optical Fiber

The above is a schematic diagram of an optical fiber, where total internal reflection occurs when light travels from the core into the cladding. Which of the following statements is correct?

a) The refractive index of the core must be greater than that of the cladding.
b) The core and cladding materials of optical fibers must be transparent materials.
c) Connecting two separate optical fibers is more complex than connecting two separate electrical wires or cables.