In a double slit experiment, when light of wavelength $400\text{nm}$ was used, the angular width of the first minima formed on a screen placed $1\text{m}$ away, was found to be $0.2^{\circ }$. What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? (${\mu }_{water}=4/3$)

1. A
   $0.266^{\circ }$
2. B
   $0.15^{\circ }$
3. C
   $0.05^{\circ }$
4. D
   $0.1^{\circ }$