Correct option is C
In an optical fiber, light remains confined to the core due to Total Internal Reflection (TIR):
• The core has a higher refractive index than the cladding.
• When light traveling in the core strikes the core-cladding boundary at an angle greater than the critical angle, it undergoes total internal reflection.
• Repeated TIR at this boundary guides the light signal along the length of the fiber with minimal loss.
