What is the maximum angle a light ray can make with the wall of the core if it is to remain inside the fiber?

Critical angle=
Arcsin(sqrt(eps2/eps1))
Where eps1 is relative permittivity of the fiber and eps2 is for the medium just outside the fiber (coating)
Note for this angle to exist
eps1>eps2 since the sin function is bound between-1 and 1. Thus the fiber is more optically dense than the jacket.

Ibelieve that the correct answer is: c. along plate boundaries

Answer it orbits high above earth to gain clearer images of light, it magnifies images relative to the human eye, it records most of the universe as it was in the past, not as it is now;