In a double slit experiment, when light of wavelength $400\mathrm{ }\mathrm{n}\mathrm{m}$ was used, the angular width of the first minima formed on a screen placed $1\mathrm{ }\mathrm{m}$ away was found to be $0.2°.$ What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? $\left({\mu }_{\mathrm{w}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}}=\frac{4}{3}\right)$

• A

  $0.266°$
• Correct answer
  B

  $0.15°$
• C

  $0.05°$
• D

  $0.1°$

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