Two transparent media A and B are separated by a plane boundary. The speed of light in those media are 1.5 × 108 m/s and 2.0 × 108 m/s, respectively. The critical angle for a ray of light for these two media is:
(1) tan-1(0.500)
(2) tan-1(0.750)
(3) sin-1(0.500)
(4) sin-1(0.750)