A double-slit apparatus is immersed in a liquid of refractive index $\mu=\frac{4}{3}$. It has slit separation of $10^{-3} m$ and distance between the plane of slits and screen is 133 cm. The slits are illuminated by a parallel beam of light of wavelength 630 nm in air. What is the fringe width?

0.63 mm

The correct answer is Option (3) → 0.63 mm