$A$ glass slab has a refractive index ' $\mu$ ' with respect to air,and the critical angle for a ray of light going from glass to air is ' $\theta$ '. If a ray of light is incident from air on the glass with an angle of incidence ' $\theta$ ',then the corresponding angle of refraction is:

• A
  $\sin^{-1}\left(\frac{1}{\sqrt{\mu}}\right)$
• B
  $\sin^{-1}\left(\frac{1}{\mu}\right)$
• C
  $\sin^{-1}\left(\frac{1}{\mu^2}\right)$
• D
  $90^{\circ}$