The solution requires an API that supports robust user authentication and authorization, geographic access restriction, and minimal latency for users in the United States.

Amazon API Gateway REST APIs are better suited for this scenario than HTTP APIs because they offer more comprehensive, built-in features for authentication and authorization, such as IAM permissions, Cognito user pools, and Lambda authorizers.

To restrict access based on geography, AWS WAF is the appropriate service. A WAF geographic match rule can be configured to allow requests only from the United States. For a regional API Gateway endpoint, the AWS WAF web ACL must be deployed in the same AWS Region as the API. Deploying this regional API in a US region ensures minimal latency for the target user base.

B. This is incorrect. For a regional resource like an API Gateway HTTP API, the AWS WAF web ACL must be configured in the same Region, not a different one.

C. This describes a configuration for an edge-optimized API deployed in a region other than us-east-1. While valid, a regional API (as implied in option A) is a more direct and standard solution that fully meets the requirements.

D. While the WAF configuration is technically correct for an HTTP API, REST APIs provide a richer feature set for the specified "user authentication and authorization" requirements, making them the superior choice.

1. AWS Documentation - Choosing between HTTP APIs and REST APIs: "REST APIs provide a wide array of features for building and managing APIs... If you need features such as API keys

per-client throttling

request validation

AWS WAF integration

or private API endpoints

use a REST API." This supports the choice of a REST API for its richer feature set related to authorization.

Source: AWS API Gateway Developer Guide

"Choosing between HTTP APIs and REST APIs."

2. AWS Documentation - Associating a web ACL with an AWS resource: "For Amazon API Gateway

you can associate a web ACL with a regional API or an edge-optimized API... For a regional API

you must create your web ACL in the same AWS Region as your API." This confirms that for a regional API

the WAF must be in the same region

validating the configuration in option A and invalidating option B.

Source: AWS WAF Developer Guide

"Associating or disassociating a web ACL with an AWS resource."

3. AWS Documentation - Geographic match rule statement: "A geographic match rule statement inspects the source IP address of a web request against a list of countries that you specify." This confirms WAF's capability to meet the geographic restriction requirement.

Source: AWS WAF Developer Guide

"Rule statement basics

" section "Geographic match rule statement."

4. AWS Documentation - Choosing an API Gateway API endpoint type to set up: "Regional API endpoints are intended for clients in the same AWS Region. When clients are in the same Region as the API

a Regional API reduces connection overhead." This supports that a regional endpoint in the US provides low latency for US-based clients.

Source: AWS API Gateway Developer Guide

"Choosing an API Gateway API endpoint type to set up."