An application runs on a single Amazon EC2 instance launched by an Auto Scaling group (min=1, max=1) in a private subnet. The application uses an Amazon RDS for MySQL DB instance. The VPC has subnets in three Availability Zones but only a single NAT gateway is deployed. The architect must ensure the application can operate across multiple Availability Zones. Which solution meets this requirement?

The correct solution ensures high availability and fault tolerance across multiple Availability Zones (AZs). Deploying additional NAT gateways in other AZs and updating route tables provides internet access for instances in those AZs, preventing a single point of failure. Converting the RDS for MySQL DB instance to Multi-AZ ensures database availability during an AZ outage. Configuring the Auto Scaling group to launch instances across AZs and setting min/max capacities to 3 distributes the application load and allows for automatic recovery. Incorrect options: Replacing the NAT gateway with a virtual private gateway is for VPN connections, not internet access for private subnets. Amazon Aurora is a good choice but doesn't address the NAT gateway or Auto Scaling group configuration for multi-AZ. Replacing the NAT gateway with a NAT instance introduces a single point of failure and management overhead. Migrating to PostgreSQL doesn't address the multi-AZ requirement. Launching additional EC2 instances manually doesn't provide automatic scaling or recovery. Enabling automatic backups for RDS is good practice but doesn't provide high availability during an AZ outage. Keeping Auto Scaling group min/max capacities at 1 defeats the purpose of multi-AZ deployment for the application instances.