A diver in a swimming pool wants to signal his distress to a perosn lying on the edge of the pool by flashing his water proof flash light then,

Options

A. he must direct the beam vertically upwards.
B. he has to direct the beam horizontally.
C. he has to direct the beam at an angle to the vertical wich is slightly less tahn he criticl angle of incidence.
D. he has to direct the beam at an angle to the vertical which is slightly more than the critical angle of incidence.