A vessel of depth $2 \mathrm{~d} \mathrm{~cm}$ is half filled with a liquid of refractive index $\mu_{1}$ and the upper half with a liquid of refractive index $\mu_{2} .$ The apparent depth of the vessel seen perpendicularly is

• A

  $\left(\frac{\mu_{1} \mu_{2}}{\mu_{1}+\mu_{2}}\right) \mathrm{d}$
• Correct answer
  B

  $\left(\frac{1}{\mu_{1}}+\frac{1}{\mu_{2}}\right) \mathrm{d}$
• C

  $\left(\frac{1}{\mu_{1}}+\frac{1}{\mu_{2}}\right) 2 \mathrm{~d}$
• D

  $\left(\frac{1}{\mu_{1} \mu_{2}}\right) 2 \mathrm{~d}$

Hence, the correct answer is option: 'B'.