Which solution will meet these requirements in the MOST operationally efficient way?
Use AWS Resource Access Manager (AWS RAM) to share the subnet that contains the database. Create an Amazon RDS Proxy endpoint for the other applications to access.
Use VPC peering to connect the VPCs of the other AWS accounts to the subnet that contains the database.
Create an Amazon S3 bucket that stores database backups. Configure replication to S3 buckets in the other accounts. Restore the backups in the other AWS accounts.
Create an interface VPC endpoint for the Amazon RDS API. Attach an endpoint policy that grants the other AWS accounts access to the database.