About the discription of the interaction flow between FusionStorage major modules, which are correct? (Multiple Choice)

About the discription of the interaction flow between FusionStorage major modules, which are correct? (Multiple Choice)
A . When the system starts, the MDC (Metadata Controller) interacts with the ZooKeeper to determine the MD
B . The master MDC and the other MDC monitor the heartbeat mutually, and the master MDC determines the successor after some MDC failure. The other MDC discovers that the master MDC fails and interacts with the ZooKeeper to determine o be promoted to the master MD
D . When the OSD (Object Storage Device) starts to query the MDC for the affiliation MDC, it reports the status to the affiliation MDC, and the affiliation MDC sends the status change to the VB
E . When the affiliation MDC fails, the master MDC designates an MDC to take over the OS
F . The same MDC can have up to two affiliation resource pools.
G . When the VBS (Virtual Block System) starts to query the primary MDC, register with the master MDC(the primary MDC maintains a list of active VBS, primary MDC synchronize the VBS list to other MDC so that the MDC can inform the VBS of the OSD state changes), confirm whether they are leaders to the MDC; VBS obtain IO View from the main MDC, the main VBS obtain metadata from the OSD, other VBS obtain the metadata from the main VBS metadata.
H . The number of MDC and the number of ZooKeeper are always the same.

Answer: ABC