Which of the following is a valid Http annotation for updating records in Apex REST?

The annotation for updating records in Apex REST is the @HttpPut annotation. This annotation indicates that the method it decorates will respond to an HTTP PUT request, which is specifically designed for updating existing resources. When a PUT request is made, it typically replaces the existing representation of a resource with the new data provided in the request body.

Using @HttpPut aligns with the RESTful principles that dictate how to interact with resources via the standard HTTP methods. This method is suitable when you need to send all the fields of the record being updated, as it generally implies that the entire resource is being updated.

In contrast, other choices like @HttpGet are used for retrieving data, @HttpPatch is utilized for updating a resource partially (only the provided fields), and @HttpDelete is for removing resources. Each of these methods serves a distinct purpose in the REST framework, making them appropriate for different scenarios, but for a full update of records in Apex REST, @HttpPut is the correct choice.