NimbusBiotech requires all model training artifacts and the EBS scratch volumes used by training instances to be encrypted with their customer-managed KMS key. They also want SageMaker training jobs to be able to read/write S3 training data encrypted with that key. Which combination of steps will correctly enforce encryption at rest for both S3 and EBS for SageMaker training?

The correct option addresses both S3 and EBS encryption requirements using the specified customer-managed KMS key. Enabling default S3 bucket encryption with SSE-KMS ensures all S3 training data is encrypted with the customer key. Passing the same KMS key ID as VolumeKmsKeyId in CreateTrainingJob encrypts the EBS volumes used by the training instances with that key. Updating the KMS key policy is crucial to grant necessary permissions to the SageMaker execution role (for S3 data access and EBS volume encryption) and the SageMaker service principal (for creating and managing encrypted EBS volumes). The other options are incorrect because: Relying on SSE-S3 or EBS encryption by default does not use the customer-managed KMS key. Client-side encryption is not a standard SageMaker practice for training data and doesn't address EBS encryption. Network isolation is a security measure for data in transit and does not enforce encryption at rest.