A company is planning to migrate an internal application to the AWS Cloud. The application will run on Amazon EC2 instances in one VPC. Users will access the application from the company's…

Assigning public IP addresses to EC2 instances inherently exposes them to the internet, violating the requirement that the application 'will not expose the application to the internet'.

Creating an Amazon Route 53 public hosted zone makes the application's DNS accessible from the internet, directly conflicting with the requirement that the solution 'will not expose the application to the internet'.

Placing EC2 instances in private subnets ensures the application is not exposed to the internet. An Amazon Route 53 private hosted zone resolves internal domain names only within the VPC and connected networks (via Route 53 Resolver endpoints to on-premises), preventing internet exposure for DNS. Route 53 health checks and associated records provide automatic failover between EC2 instances, meeting all specified requirements efficiently.

While an NLB can provide load balancing and failover, Route 53 can directly perform health checks and failover for EC2 instances' private IPs, making an NLB an additional component that is not strictly necessary for the described failover requirement and increasing complexity. The provided choice D in the question was truncated.