A company runs a critical application on EC2 instances behind an ALB. The EC2 instances are in an Auto Scaling group and access an Amazon RDS DB instance. All resources are currently in a single Availability Zone. You must update the design to use a second Availability Zone to make the application highly available. Which solution achieves this?

To achieve high availability, resources must be distributed across multiple Availability Zones (AZs). Subnets are AZ-specific, so you need a separate subnet in each AZ for your EC2 instances. The Auto Scaling group should be configured to launch instances into these subnets, ensuring even distribution. For the RDS database, Multi-AZ deployment is the correct solution as it automatically provisions a synchronous standby replica in a different AZ, handling failover without manual intervention. Incorrect options: "Configure the DB instance with connections to each network" is not a standard or effective way to make RDS highly available; Multi-AZ is the native solution. "Subnets that extend across both Availability Zones" is incorrect; subnets are always confined to a single AZ.