A web application runs on EC2 instances behind an ALB in an Auto Scaling group across multiple AZs and uses an Amazon RDS for MySQL instance. Route 53 points to the ALB with an alias record. Company policy now requires a geographically isolated DR site with an RTO of 4 hours and an RPO of 15 minutes, with minimal changes to the application stack. Which DR approach satisfies these requirements with the least application changes?

The correct option provides a multi-Region disaster recovery (DR) strategy that meets the RTO and RPO requirements with minimal application changes. Creating a duplicate environment in another Region (pilot light or warm standby) ensures geographical isolation. An RDS read replica in the DR Region, configured for the DR environment, allows for a low RPO (15 minutes) as data is continuously replicated. Promoting the read replica to a standalone primary instance during a disruption is a quick process, contributing to the 4-hour RTO. Route 53 with a health-check-based failover policy automates the traffic redirection, minimizing manual intervention. The other options are incorrect because: Duplicating in another Availability Zone does not provide geographical isolation. Using latency-based routing for DR is not appropriate; failover routing is needed. Relying on restoring an RDS snapshot in a disaster would likely exceed the 4-hour RTO due to the time required for snapshot restoration.