What is the difference between SAN (block) and NAS (file) backup procedures using snapshots?

A.
In the SAN (block) scenario, the file system is controlled by the host and must be consistent when the snapshot is taken.

B.
Nothing; they are the same.

C.
In the NAS (file) scenario, the file system is controlled by the host and must be consistent when the snapshot is taken.

D.
None of the above