The correct answer is B, AWS Systems Manager Session Manager. This service provides secure and auditable access to EC2 instances without the need to open inbound SSH ports or manage SSH keys. It allows users to connect to their instances through the AWS Management Console, CLI, or SDKs, and it integrates with IAM for fine-grained access control. All session activities are recorded in AWS CloudTrail for compliance and auditing purposes, enhancing the security and audit posture of the company's EC2 instances.