You issued the following command to mount the DATA disk group in restricted mode： ALTER DISKGROUP data MOUNT RESTRICT； What is the implication of this command？（）

A. The client RDBMS instance can access the file as a read-only file.
B. A new disk cannot be added to a disk group.
C. A disk in a disk group can be taken offline.
D. The client RDBMS instance cannot access the files in the disk group.