Where does cross-region replication require versioning to be enabled?

Answer options:

A.Only on Destination bucket.
B.Versioning is useful to avoid accidental deletes and not a requirement for replicating across regions.
C.Only on Source bucket.
D.Both on Source and Destination buckets.

Answer: D
Cross-region replication is a bucket-level configuration that enables automatic, asynchronous copying of objects across buckets in different AWS Regions. We refer to these buckets as source bucket and destination bucket. These buckets can be owned by different AWS accounts.
For more information on AWS S3 cross-region replication, refer to the documentation here.
https://docs.aws.amazon.com/AmazonS3/latest/dev/crr.html