In the 2.5G MSP ring consisting of four MSTP sites, when a protection switching occurs, which of the following statements about the alarm reporting is correct?
A . The PS alarm is reported on the tributary board.
B . The APS-INDI alarm is reported on the XCS board.
C . The APS-INDI alarm is reported on the system control board.
D . The APS-INDI alarm is reported on the line board.
Answer: B