Which disaster recovery strategy will require the LEAST amount of changes to the application stack?

An application runs on Amazon EC2 instances behind an Application Load Balancer. Amazon RDS MySOL is used on the backend. The instances run in an Auto Scaling group across multiple Availability Zones. The Application Load Balancer health check ensures the web servers are operating and able to make read/write SQL connections. Amazon Route 53 provides DNS functionality with a record pointing to the Application Load Balancer. A new policy requires a geographically isolated disaster recovery site with an RTO of 4 hours and an RPO of 15 minutes.

Which disaster recovery strategy will require the LEAST amount of changes to the application stack?
A . Launch a replica stack of everything except RDS in a different Availability Zone. Create an RDS read-only replica in a new Availability Zone and configure the new stack to point to the local RDS instance. Add the new stack to the Route 53 record set with a failover routing policy.
B. Launch a replica stack of everything except RDS in a different region. Create an RDS read-only replica in a new region and configure the new stack to point to the local RDS instance. Add the new stack to the Route 53 record set with a latency routing policy.
C. Launch a replica stack of everything except RDS in a different region. Upon failure, copy the snapshot over from the primary region to the disaster recovery region. Adjust the Amazon Route 53 record set to point to the disaster recovery region’s Application Load Balancer.
D. Launch a replica stack of everything except RDS in a different region. Create an RDS
read-only replica in a new region and configure the new stack to point to the local RDS instance. Add the new stack to the Amazon Route 53 record set with a failover routing policy

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Answer: D