Which AWS service is always provided at no charge?
Amazon S3
AWS Identity and Access Management (IAM)
Elastic Load Balancers
AWS WAF
Explanations:
Amazon S3 charges for storage, requests, and data transfer. While there is a free tier available for the first 12 months, usage beyond that incurs costs.
AWS Identity and Access Management (IAM) is always provided at no charge. There are no costs associated with creating IAM users, groups, or roles, and using IAM features.
Elastic Load Balancers (ELB) incur costs based on usage, including data processed, number of connections, and load balancer hours.
AWS WAF (Web Application Firewall) charges based on the number of web access control lists (ACLs) and rules, as well as the number of requests processed.
I calculate that the answer is:
AWS Identity and Access Management (IAM)