In a Young's double slit experiment set up the 10th maxima is 3 cm from the central maxima . If the whole set up is immersed in a liquid of refractive index $\mu=1.5$ What will be the new fring width

Question

(a) will be same

(b)will be 2 mm

(c)will be 4 mm  

(d)will be 1mm