A circular beam of diameter $d=2 \;cm$ falls on a plane surface of glass . The angle of incidence is $60^{\circ}$ and refractive index of glass is $\mu=\large\frac{3}{2}$. The diameter of the refracted beam is ,

Question

$(a)\;2\;cm \\ (b)\;6\;cm \\ (c)\;5.2\;cm \\ (d)\;3.26\;cm$