Which One of the Following Expressions Determines the Critical Angle $\theta$

Multiple Choice

Which one of the following expressions determines the critical angle for quartz (n = 1.5) immersed in oil (n = 1.1) ?

A) $\theta$ _c = 1.5/1.1
B) $\theta$ _c = sin^-1 (1.1/1.5)
C) $\theta$ _c = sin (1.1/1.5)
D) $\theta$ _c = tan^-1 (1.1/1.5)