A developer at a company recently created a serverless application to process and show data from business reports. The application's user interface (UI) allows users to select and start processing the flies. The UI displays a message when the result is available to view. The application uses AWS Step Functions with AWS Lambda functions to process the files. The developer used Amazon API Gateway and Lambda functions to create an API to support the UI.
The company's UI team reports that the request to process a file s often returning timeout errors because of the size or complexity of the files. The UI team wants the API to provide an immediate response so that the UI can display a message while the files are being processed. The backend process that is invoked by the API needs to send an email message when the report processing is complete.
What should the developer do to configure the API to meet these requirements?

A. Change the API Gateway route to add an X-Amz-Invocation-Type header with a static value of `Event' in the integration request. Deploy the API Gateway stage to apply the changes.
B. Change the configuration of the Lambda function that implements the request to process a file. Configure the maximum age of the event so that the Lambda function will run asynchronously.
C. Change the API Gateway timeout value to match the Lambda function timeout value. Deploy the API Gateway stage to apply the changes.
D. Change the API Gateway route to add an X-Amz-Target header with a static value of `Async' in the integration request. Deploy the API Gateway stage to apply the changes.