In Fresnel bi prism experiment if prism angle $\alpha=1^{\circ}, \mu=1.54$ distance between prism and sources a is $0.3\;m$ and wave length $ \lambda= 180 \pi \;nm$ find the fringe width, distance between screen and prism $b= 0.7 \;m$

Question

$(a)\;10^{-4}\;m \\ (b)\;10^{-3}\;mm \\ (c)\;10^{-4}\;mm \\ (d)\;10^{-3}\;m$