The Index of Refraction Is Related to the Prism Angle $\delta$

Multiple Choice

The index of refraction is related to the prism angle and the angle of minimum deviation by n = sin ½( $\delta$ + $\phi$ ) /sin ½ $\phi$
The angle of minimum deviation in the figure is angle

A) 1
B) 2
C) 3
D) 4
E) 5