A right angled prism ABC is dipped in water . such that the surface AB is in air as shown. A ray of light is normally. What must be the possible value of $\theta$ so that the say gets totally reflected at AC to reach surface BC.

Question

$(a)\;\sin \theta \geq \frac{8}{9} \\ (b)\;\frac{2}{3} < \sin \theta < \frac{8}{9} \\ (c)\;\sin \theta \leq \frac{2}{3} \\ (d)\;\sin \theta \geq \frac{4}{3}$