When the main control board is configured with a single board, which step is required to replace the single board than when the main control board is configured with a dual configuration?

When the main control board is configured with a single board, which step is required to replace the single board than when the main control board is configured with a dual configuration?
A . Download the original configuration data
B . Ensure that the host software version is the same before and after the replacement. If it is inconsistent, please upgrade and replace the single board software first.
C . Check the consistency of network management and network element data.
D . Query the board alarm and confirm that the original alarm has been cleared.

Answer: A