The company needs multi-Region data persistence with immediate propagation and minimal operational overhead. For S3, the correct mechanism is S3 replication (Cross-Region Replication or Same-Region Replication), which continuously and asynchronously replicates new objects as they are written. Configuring two-way replication between the primary and secondary Region buckets ensures that objects written in either Region are replicated to the other automatically without custom code.

For DynamoDB, the native solution for multi-Region replication is DynamoDB global tables . Global tables provide multi-master, multi-Region replication with low-latency reads and writes in each Region and automatic propagation of changes. Converting existing tables into global tables and adding the secondary Region as a replica gives immediate, managed cross-Region replication with minimal maintenance.

Option A combines these two fully managed features: two-way S3 replication and DynamoDB global tables. This yields the highest operational efficiency.

Options B, C, and D rely on S3 Batch Operations or DynamoDB Streams + Lambda to manually copy data cross-Region. These approaches add complexity, custom code, and operational risk, and they are less suitable when AWS provides managed replication mechanisms specifically designed for this purpose.

Therefore, Option A is the correct and most efficient solution.