[单选题]
An optic fiber is made of clear plastic with i 9 dm6)y2tho(ati *xxjndex of refraction of 1.50. Fo4n6w629jrarf u7skyk*f q9eg r what angle of incidence will light yq 6nk gue*9fka7r2 9fjwsr64remain within the plastic "guide"?
A. $>23.4^{\circ}$
B. $>38.3^{\circ}$
C. $>40.3^{\circ}$
D. $>41.8^{\circ}$
