How should the application be deployed while minimizing the number of resources to manage?

Explanations:

Creating separate API Gateway and Lambda functions for each environment increases the number of resources to manage, which can complicate deployments and lead to higher costs and maintenance overhead.

Assigning a separate Region for each environment not only increases resource management complexity but also leads to higher latency for users if the Regions are geographically distant, in addition to increasing costs due to multiple Regions.

Creating one API Gateway with multiple stages and one Lambda function with multiple aliases minimizes resource management. This approach allows for efficient environment management, easy deployment, and consistent usage of resources across all environments.

Using a REST parameter to identify the environment can lead to confusion and potential security issues, as the same resources are used across environments, making it difficult to manage configurations and deployments safely and effectively.