A. This eliminates the need for the traffic to go over the internet, providing an added layer of security.
B. It is important to restrict access to the bucket and its objects only to authorized entities.
C. This helps maintain the confidentiality of the sensitive user information by limiting access to authorized resources.
D. In this case, since the EC2 instances are accessing the S3 bucket from within the VPC, using IAM user credentials is unnecessary and can introduce additional security risks.
E. a NAT instance to access the S3 bucket adds unnecessary complexity and overhead.
In summary, the recommended steps to provide secure access to the S3 from the application tier running on EC2 inside a VPC are to configure a VPC gateway endpoint for S3 within the VPC (option A) and create a bucket policy that limits access to only the application tier running in the VPC (option C).