Which status code would indicate a client error in an API response?

• A. 200
• B. 301
• C. 404
• D. 503

Answer: (C)

A status code indicating a client error is represented by the 4xx class of status codes, with 404 specifically signifying that the requested resource could not be found on the server. This response typically occurs when the client sends a request for a resource that does not exist, indicating to the client that there is an issue with the request itself, rather than with the server.

In the context of API responses, a 404 status code not only informs the client that the URL in the request does not map to any available resource but also helps in debugging or handling errors gracefully on the client side, prompting further actions such as correcting the URL or handling the logic accordingly.

The other status codes provided serve different purposes: 200 signifies a successful request where the response is as expected, 301 indicates that a resource has been permanently moved to a different URL, and 503 is used to indicate that the server is currently unable to handle the request, which points to a server-side issue rather than a client error.