A network is configured with an optical line protection group. The initial difference between the main and backup input optical values is 2db and the main and backup input optical difference switching threshold is 5db. Which of the following conditions will trigger the switchover?
A . Optical power of the main channel-Optical power of the standby channel = 4db
B . Optical power of the main channel-Optical power of the standby channel = -4db
C . Optical power of the main channel-Optical power of the standby channel = -2db
D . Optical power of the main channel-Optical power of the standby channel = 2db
Answer: B