A frontend developer needs to write integration tests that exercise both success and error HTTP responses from an API Gateway-backed serverless backend. The tests should cover positive and negative cases with minimal setup effort while the logic tier is still under development. Which approach requires the least development effort?

The correct option leverages API Gateway's built-in mock integration feature. This allows developers to define static responses directly within API Gateway, including different HTTP status codes and body content, without needing any backend compute. By using a simple integration request mapping, the developer can dynamically switch between success and error responses based on a query parameter or header, minimizing setup effort and providing immediate feedback for frontend integration tests. The other options are less efficient: Creating two separate mock integration resources doubles the configuration effort. Creating Lambda functions introduces unnecessary compute and deployment overhead for simple mock responses. Referencing a Lambda from a mock integration is not a standard or efficient pattern; mock integrations are designed to return static responses directly.