A network is configured with an optical line protection group. The initial difference between the primary and standby input optical signals is 2db, and the primary and standby input optical difference switching threshold is 5db. Which of the following situations will trigger switching?

A network is configured with an optical line protection group. The initial difference between the primary and standby input optical signals is 2db, and the primary and standby input optical difference switching threshold is 5db. Which of the following situations will trigger switching?
A . Main channel optical power minus standby channel optical power = 4db
B . Main channel optical power minus standby channel optical power = -4db
C . Main channel optical power minus standby channel optical power = -2db
D . Main channel optical power minus standby channel optical power = 2db

Answer: B