Each quarter of a vessel of depth H is filled with liquids of the refractive indices\[{{n}_{1}},{{n}_{2}},{{n}_{3}}\,\,and\,\,{{n}_{4}}\] from the bottom respectively. The apparent depth of the vessel when looked normally is [AMU (Engg.) 2000]

• A. \[\frac{H({{n}_{1}}+{{n}_{2}}+{{n}_{3}}+{{n}_{4}})}{4}\]
• B. \[\frac{H\left( \frac{1}{{{n}_{1}}}+\frac{1}{{{n}_{2}}}+\frac{1}{{{n}_{3}}}+\frac{1}{{{n}_{4}}} \right)}{4}\]
• C. \[\frac{({{n}_{1}}+{{n}_{2}}+{{n}_{3}}+{{n}_{4}})}{4H}\]
• D. \[\frac{H\left( \frac{1}{{{n}_{1}}}+\frac{1}{{{n}_{2}}}+\frac{1}{{{n}_{3}}}+\frac{1}{{{n}_{4}}} \right)}{2}\]