What AWS feature can help with data encryption at rest?

The choice of AWS Key Management Service (KMS) as the feature that helps with data encryption at rest is accurate because KMS is specifically designed to create and manage cryptographic keys for your applications and services. It provides the ability to easily encrypt data with encryption keys and manage access to those keys securely.

KMS allows you to encrypt data stored in AWS services such as Amazon S3, Amazon EBS, and Amazon RDS, ensuring that sensitive information is stored securely and meets compliance requirements. By using KMS, you can control who can access and use the keys, providing a managed and centralized way to handle encryption.

The other features mentioned do not focus primarily on data encryption at rest. AWS Shield is primarily a security service focused on DDoS protection; AWS Identity and Access Management (IAM) is used for managing user access and permissions; and AWS CloudTrail provides monitoring and logging of account activity rather than directly relating to data encryption. Thus, KMS stands out as the most relevant service for managing encryption keys and securing data at rest.