Answer: Lambda Aliases, Stage Variables

Overall explanation Correct options: Stage Variables Stage variables are name-value pairs that you can define as configuration attributes associated with a deployment stage of an API. They act like environment variables and can be used in your API setup and mapping templates. With deployment stages in API Gateway, you can manage multiple release stages for each API, such as alpha, beta, and production. Using stage variables you can configure an API deployment stage to interact with different backend endpoints. For example, your API can pass a GET request as an HTTP proxy to the backend web host (for example, http://example.com). In this case, the backend web host is configured in a stage variable so that when developers call your production endpoint, API Gateway calls example.com. When you call your beta endpoint, API Gateway uses the value configured in the stage variable for the beta stage and calls a different web host (for example, beta.example.com). Lambda Aliases A Lambda alias is like a pointer to a specific Lambda function version. Users can access the function version using the alias ARN. Lambda Aliases allow you to create a "mutable" Lambda version that points to whatever version you want in the backend. This allows you to have a "dev", "test", prod" Lambda alias that can remain stable over time. Incorrect options: Lambda Versions - Versions are immutable and cannot be updated over time. So this option is not correct. Lambda X-Ray integration - This is good for tracing and debugging requests so it can be looked at as a good option for troubleshooting issues in the future. This is not the right fit for the given use-case. Mapping Templates - Mapping template overrides provides you with the flexibility to perform many-to-one parameter mappings; override parameters after standard API Gateway mappings have been applied; conditionally map parameters based on body content or other parameter values; programmatically create new parameters on the fly, and override status codes returned by your integration endpoint. This is not the right fit for the given use-case.

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