An SQS FIFO consumer processes independent orders. Events for the same order must remain ordered, while unrelated orders should process concurrently. Which message-group strategy is suitable?

1. Put all orders in one group to maximize parallel processing of unrelated orders.
2. Omit group identity and expect the service to infer order ownership from arbitrary body fields.
3. Use order_id as MessageGroupId and make business processing idempotent.
4. Assign every event a different random group and rely on global ordering.