Match each Response Code with its correct meaning: OK—Standard response for successful requests.

The response code that represents "OK" as a standard response for successful requests is indeed 200. This HTTP status code indicates that the request was successful and that the server has returned the requested data. It is the most common response code used to signify that a request has been processed without errors, making it a critical part of the communication between client and server in web applications and APIs.

The other codes mentioned serve different purposes: 201 indicates that a resource has been successfully created, often returned in response to a POST request. 204 signifies that the request was successful, but there is no content to return, which is useful for operations that do not need to send back data, such as DELETE requests. Lastly, 400 represents a client error, indicating that the request sent to the server was malformed or invalid in some way, resulting in failure. Thus, 200 is specifically tied to successful retrieval, aligning with the "OK" designation.