Correct answer - "Security Groups" : Security Groups are used for several services such as EC2
and RDS where they act as a firewall to restrict/allow connections to these services. S3 is not
like managing a server behind a firewall, in fact S3 is a object storage service that is managed
by AWS and designed to scale.
"IAM Policies" - With IAM policies you can grant an IAM user in your AWS account to access one of
your buckets and allow the user to add, update, and delete objects
"ACLs" - You can attach S3 ACLs to individual objects within a bucket to manage permissions for
those objects.
"Bucket Policies" - With Bucket policies you can grant cross-account access to your S3
environment, without using IAM roles