Which is not a restriction on AWS EBS Snapshots?

volumes and snapshots. http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-modifying-snapshot-permissions.html

A.
Snapshots which are shared cannot be used as a basis for other snapshots.

B.
You cannot share a snapshot containing an AWS Access Key ID or AWS Secret Access Key.

C.
You cannot share unencrypted snapshots.

D.
Snapshot restorations are restricted to the region in which the snapshots are created.

Explanation:
Explanation/Reference:
Snapshots shared with other users are usable in full by the recipient, including but limited to the ability to base modified