A. Create a read replica of the DB instance, and enable encryption. When the read replica is available, promote the read replica and update the endpoint that is used by the application. Delete the unencrypted DB instance.
B. Take a snapshot of the DB instance. Make an encrypted copy of the snapshot. Restore the encrypted snapshot. When the new DB instance is available, update the endpoint that is used by the application. Delete the unencrypted DB instance.
C. Create a new encrypted DB instance. Perform an initial data load, and set up logical replication between the two DB instances When the new DB instance is in sync with the source DB instance, update the endpoint that is used by the application. Delete the unencrypted DB instance.
D. Convert the DB instance to an Amazon Aurora DB cluster, and enable encryption. When the DB cluster is available, update the endpoint that is used by the application to the cluster endpoint. Delete the unencrypted DB instance.