A fiber optic line is composed of a core with an index of refraction of 1.47 and cladding with an index of 1.31. Which one of the following relations best describes angles of incidence ? that will result in total internal reflection within the fiber optic line?
a. ? > 63°
b. ? < 27°
c. ? > 27°
d. 0 ? ? ? 90°
e. ? < 63°