A Cladded Optical Fiber for Transmitting Red Light Is Constructed $\circ$

A cladded optical fiber for transmitting red light is constructed by placing a cladding material around a round plastic optical fiber.If the index of refraction of the plastic fiber core is 1.6 and the index of refraction of the cladding is 1.2,what is the critical angle for light to transport through the plastic fiber core without loss?

A) 34 ^$\circ$
B) 39 ^$\circ$
C) 41 ^$\circ$
D) 49 ^$\circ$
E) 56 ^$\circ$