A lens made of material of refractive index $\mu =\large\frac{3}{2} $ when placed in air behaves as shown in figure (1) . But when placed in a medium of refractive index $\mu_s$ it behaves as shown in figure (2) . Then the value of $\mu_s $ is

Question

 

$(a)\;\mu_s=1.75 \\ (b)\;\mu_s =1.6 \\ (c)\;\mu_s =2 \\ (d)\;\mu_s=1.45 $