Which service is used to centrally manage users and permissions in AWS?

The correct answer is AWS Identity and Access Management (IAM) because this service is specifically designed to provide centralized control over user identities and permissions within AWS. With IAM, you can create and manage AWS users and groups, and use policies to grant or deny access to AWS resources based on the principle of least privilege. This allows organizations to manage security credentials and implement fine-grained access control mechanisms effectively.

IAM enables administrators to define who can access which AWS resources (like S3 buckets, EC2 instances, etc.) under what conditions. It supports the use of roles for applications running on Amazon EC2, making it easier to manage permissions without embedding sensitive credentials in applications. Furthermore, IAM integrates seamlessly with other AWS services to allow for a coherent access management strategy across an entire AWS environment.

Other services mentioned in the options serve different purposes: AWS Glue Data Catalog is a metadata repository for managing data assets, Amazon VPC is focused on creating isolated networks within AWS, and Amazon S3 is used primarily for storing and retrieving data objects. None of these provide the user and permission management functionalities that IAM offers, highlighting IAM's unique and critical role in AWS.