为自己加油

Examine these queries and their output:

After a system crash, an instance restart and an attempted opening of the PDBs

Result in:

Which two are true? (Choose two.)

A.
Data file 24 can be recovered while PDB2 is opened.
B.
Data file 24 must be recovered while the CDB is opened.
C.
Data file 24 can be recovered while CDB$ROOT and PDB$SEED are opened.
D.
Data file 24 cannot be recovered while the CDB is opened.
E.Data file 24 must be recovered while PDB2 is closed.