Light travelling through three transparent substances follows the path shown in the figure. Assuming that total internal reflection does take place on the bottom surface of medium 2, arrange the refractive index in the increasing order.
A. `mu_(1) lt mu_(2) lt mu_(3)`
B. `mu_(2) lt mu_(1) lt mu_(3)`
C. `mu_(1) lt mu_(3) lt mu_(3)`
D. `mu_(3) lt mu_(1) lt mu_(2)`