Answer is D ladies and gentlemen. While guard duty helps to monitor s3 for potential threats its a reactive action. We should always be proactive and not reactive in our solutions so D, block public access to avoid any possibility of the info becoming publicly accessible

Answer D is the correct solution that meets the requirements. The S3 Block Public Access feature allows you to restrict public access to S3 buckets and objects within the account. You can enable this feature at the account level to prevent any S3 bucket from being made public, regardless of the bucket policy settings. AWS Organizations can be used to apply a Service Control Policy (SCP) to the account to prevent IAM users from changing this setting, ensuring that all S3 objects remain private. This is a straightforward and effective solution that requires minimal operational overhead.

its 1 aws account, how could D be the answer?

Use the S3 Block Public Access feature on the account level. Use AWS Organizations to create a service control policy (SCP) that prevents IAM users from changing the setting. Apply the SCP to the account

Use the S3 Block Public Access feature on the account level. Use AWS Organizations to create a service control policy (SCP) that prevents IAM users from changing the setting. Apply the SCP to the account

A is correct!

https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-control-block-public-access.html

This is the most effective solution to meet the requirements.

Option D provided real solution by using bucket policy to restrict public access. Other options were focus on detection which wasn't what was been asked

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