A company creates an Amazon API Gateway API and shares the API with an external development team. The API uses AWS Lambda functions and is deployed to a stage that is named Production. The external…

Configuring the API to send requests to Amazon Simple Queue Service (Amazon SQS) queues would fundamentally change the API's behavior from synchronous to asynchronous and would require reworking the Lambda functions to process SQS messages.

Configuring provisioned concurrency for Lambda functions addresses cold start latency and performance, but it does not limit the number of API calls or control costs; in fact, it incurs additional costs.

While AWS WAF Regional can provide rate-limiting functionality, it is primarily a security service, and a usage plan within API Gateway is a more direct, cost-effective, and simpler mechanism for managing specific consumer usage limits.

An API Gateway API Key combined with a usage plan is the most effective and cost-efficient solution to limit API usage and costs for a specific consumer without modifying backend Lambda functions, as it allows defining throttling limits (e.g., requests per second, burst) and quotas (e.g., total requests over a month) directly on the API Gateway.