A company wants to log in securely to Linux Amazon EC2 instances. How can the company accomplish this goal?

SSH (Secure Shell) keys provide a highly secure and standard method for authenticating and logging into Linux Amazon EC2 instances. Users generate a cryptographic key pair, keep the private key secure on their local machine, and the public key is placed on the EC2 instance, enabling encrypted and password-less authentication over SSH.

Using a VPN provides a secure network connection to the AWS environment but is a transport layer security measure, not the direct method for authenticating a login session to a Linux EC2 instance itself.

End-to-end encryption is a broad security concept ensuring data is encrypted from source to destination, but it's not the specific authentication mechanism for logging into a Linux EC2 instance.

Amazon Route 53 is a highly available and scalable cloud Domain Name System (DNS) web service, which is unrelated to logging into EC2 instances.