A. Create dedicated S3 access points and access point policies for each application.

Explanation: S3 Access Points: These provide a way to manage access to shared data sets in Amazon S3. Each access point has a unique hostname and a policy that is specific to the use case, allowing for granular control over access to data. Access Point Policies: These policies can be tailored to restrict access to specific prefixes within an S3 bucket, ensuring that each application only has access to its designated prefix.

Answer A By creating separate access points for each application, you can enforce access controls specific to their respective prefixes while minimizing administrative complexity. This approach provides a clean separation of permissions and reduces the risk of misconfigurations. Options B, C, and D are not as efficient or straightforward: Option B (S3 Batch Operations) involves setting ACL permissions for each object individually, which can be cumbersome and time-consuming. Option C (replicating objects to new S3 buckets) introduces additional buckets and replication rules, increasing management overhead. Option D (replicating objects and creating dedicated S3 access points) adds unnecessary complexity by combining replication and access point creation.

Answer B Taking into consideration that we have "numerous applications" (10,100,1000?) and we need meet requirements with the LEAST operational overhead I would go into authomatization of operations hence Batch Operations seems to be good choice. https://aws.amazon.com/blogs/storage/updating-amazon-s3-object-acls-at-scale-with-s3-batch-operations/

https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-points-policies.html

Create an S3 Batch Operations job to set the ACL permissions for each object in the S3 bucket