A Company Has Mandated a Global Encryption-At-Rest Policy

Multiple Choice

A company has mandated a global encryption-at-rest policy. A DevOps engineer has been tasked to ensure that new data uploaded to both new and existing Amazon S3 buckets is encrypted at rest across the company's AWS Organizations organization. There are a number of legacy applications deployed on AWS that use Amazon S3 and do not store data encrypted at rest. These applications MUST continue to operate. The engineer must ensure S3 encryption at rest across the organization without requiring an application code change. How should this be accomplished with MINIMAL effort?

A) Develop an AWS Lambda function that lists all Amazon S3 buckets in a given account and applies default encryption to all S3 buckets that either do not have it enabled or to those with an S3 bucket policy that do not explicitly deny put-object requests without server-side encryption. Deploy the Lambda function along with an Amazon EventBridge (Amazon CloudWatch Events) scheduled rule with AWS CloudFormation StackSets to all accounts within the organization.
B) Enable the AWS Config s3-bucket-server-side-encryption-enabled managed rule that checks for S3 bucket that either do not have S3 default encryption enabled or those with an S3 bucket policy that does not explicitly deny put-object requests without server-side encryption. Add the AWS-EnabledS3BucketEncryption remediation action to the AWS Config rule to enable default encryption on any S3 buckets that are not complaint. Use AWS Config organizations integration to deploy the rule across all accounts in the organization.
C) Enable an AWS Config custom rule that checks for S3 buckets that do not have a bucket policy denying access to s3:PutObject unless the x-amz-server-side-encryption S3 condition is met with an AES 256 value or x-amz-server-side-encryption is not present. Add a custom remediation action to the AWS Config rule that will apply the bucket policy if the S3 bucket is non-complaint. Use AWS Config organizations integration to deploy the rule across all accounts in the organization.
D) Write an SCP that denies access to s3:PutObject unless either the x-amz-server-side-encryption S3 condition is met with an AES 256 value or x-amz-server-side-encryption is not present. Apply the SCP to the root of the organization to enforce the policy across the entire organization.