In a double slit experiment, the angular width of a fringe is found to be $0.2 ^{\circ}$ on a screen placed 1 m away . The wave length of light used is 600 nm. What will be the angular width of the fringe if the entire experimental approaches is immerse in water ? Take refractive index of water to be 4/3 ?

Question

$\begin{array}{1 1} 1.5^{\circ} \\ 15^{\circ} \\ 0.15 ^{\circ} \\ none of these \end{array} $