When provisioning storage for Cloud Volumes ONTAP In Azure using Cloud Manage, why Is the maximum usable size of a FlexVol volume 76.55

When provisioning storage for Cloud Volumes ONTAP In Azure using Cloud Manage, why Is the maximum usable size of a FlexVol volume 76.55
A . The limit is actually 76.8 T
B . but a small portion of the volume is set aside for meta data.
C . Cloud Manager sets by default an aggregate free space ratio of 10 percent.
D . Twenty percent of the disk space is reserved for overhead.
E . Data ONTAP sets this number as a hard encoded limit in the storage subsystem.

Answer: D