Storing copies of data in multiple geographic locations to protect against regional disasters. Like keeping important documents in safe deposit boxes in different cities.
Cloud storage services keep your files in data centers across different continents so earthquakes or power outages can't destroy your data.
All four options keep copies of object data in separate geographic locations for disaster recovery. AWS S3 CRR replicates between chosen regions; Azure GRS/RA-GRS replicates to a paired region (RA-GRS adds read access to the secondary); Google Cloud dual-region stores data redundantly across two regions you select; OCI Object Storage Replication asynchronously replicates buckets between regions.