Fiber Optic Cable Is in the Form of a Cylinder $^{\circ}$

Multiple Choice

Fiber optic cable is in the form of a cylinder of fiber with index of refraction 1.67 and cladding around the outside of index of refraction 1.45.What is the maximum angle for light rays inside the fiber with respect to the cable's axis for which the light will be fully transmitted thanks to total internal reflection?

A) 30 $^{\circ}$
B) 60 $^{\circ}$
C) 41 $^{\circ}$
D) 49 $^{\circ}$