Consider a tank made of glass(reiractive index 1.5) with a thick bottom. It is filled with a liquid of refractive index $\mu$. A student finds that, irrespective of what the incident angle $i$ (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of $\mu$ is :
(1) $3\over\sqrt5$
(2) $5\over\sqrt3$
(3) $\sqrt{5\over3}$
(4) $4\over3$