You need to modify a client application that consumes a Windows Communication Foundation (WCF) service. The service metadata is no longer available. You need to modify the previously generated proxy to include asynchronous calls to the service. What should you do? （）

• A、Update the service reference with the Generate asynchronous operations option.
• B、Create a partial class for the previously generated proxy and include the new asynchronous methods.
• C、Create a class with the same name as the previously generated proxy and add the new asynchronous methods. Add the new class to a namespace that is different from the original proxy.
• D、Create a class with the same name as the previously generated proxy and add the new asynchronous methods as partial methods. Add the new class to a namespace that is different from the original proxy.