A Windows Azure application includes a single-threaded worker role that has multiple instances. The worker role hosts a Windows Communication Foundation （WCF） service. Each request to the WCF service takes several seconds to complete.   You need to recommend an approach for ensuring that worker role instances do not receive requests while processing.  What should you recommend？（）

• A、 Close the WCF endpoint.
• B、 Throw an exception to cancel the request.
• C、 Redirect incoming requests to a different worker role instance.
• D、 Remove the worker role instance from the load balancer rotation.