Amazon S3 Block Public Access configured at the AWS account level is the recommended and most effective approach to protect data stored in Amazon S3 while minimizing operational overhead. AWS Security Specialty documentation explains that S3 Block Public Access provides centralized, preventative controls designed to block public access to S3 buckets and objects regardless of individual bucket policies or object-level ACL configurations. When enabled at the account level, these controls automatically apply to all existing and newly created buckets, significantly reducing the risk of accidental exposure caused by misconfigured permissions.

The AWS Certified Security – Specialty Study Guide emphasizes that public access misconfiguration is a leading cause of data leaks in cloud environments. Account-level S3 Block Public Access acts as a guardrail by overriding any attempt to grant public permissions through bucket policies or ACLs. This eliminates the need to manage security settings on a per-bucket or per-object basis, thereby reducing administrative complexity and human error.

Configuring Block Public Access at the object level, as in option B, requires continuous monitoring and manual configuration, which increases operational overhead. Disabling ACLs alone, as described in option C, does not fully prevent public access because bucket policies can still allow public permissions. Using AWS PrivateLink, as in option D, controls network access but does not protect against public exposure through misconfigured S3 policies.

AWS security best practices explicitly recommend enabling S3 Block Public Access at the account level as the primary mechanism for preventing unintended public data exposure with minimal management effort.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon S3 Security Best Practices Documentation

Amazon S3 Block Public Access Overview

AWS Well-Architected Framework – Security Pillar