A rectangular glass slab ABCD, of refractive index \[{{n}_{1}}\] is immersed in water of refractive index\[{{n}_{2}}({{n}_{1}}>{{n}_{2}})\]. A ray of light in incident at the surface AB of the slab as shown. The maximum value of the angle of incidence\[{{\alpha }_{\max }}\] such that the ray comes out only from the other surface CD is given by

• A. \[{{\sin }^{-1}}\left[ \frac{{{n}_{1}}}{{{n}_{2}}}\cos \left( {{\sin }^{-1}}\frac{{{n}_{2}}}{{{n}_{1}}} \right) \right]\]
• B. \[{{\sin }^{-1}}\left[ {{n}_{1}}\cos \left( {{\sin }^{-1}}\frac{1}{{{n}_{2}}} \right) \right]\]
• C. \[{{\sin }^{-1}}\left( \frac{{{n}_{1}}}{{{n}_{2}}} \right)\]
• D. \[{{\sin }^{-1}}\left( \frac{{{n}_{2}}}{{{n}_{1}}} \right)\]