A Glass Fiber Can Act as a Pipe for Light-Light

A glass fiber can act as a pipe for light-light that enters the fiber at its end follows the fiber almost indefinitely without escaping through the fiber's surface. The light follows the fiber because

A) electric charges in the glass attract the light and prevent it from accelerating outward, away from the center of the fiber.
B) the fiber contains many tiny diverging lenses that focus the light back into the fiber over and over again.
C) whenever it tries to leave the glass at a shallow angle, it's perfectly reflected.
D) the fiber contains many tiny converging lenses that focus the light back into the fiber over and over again.