A small business owner would like to start keeping track of the orders received on a WebSphere Commerce V5.6 site.  The owner would like to receive an e-mail each time an order is completed.  Which of the following subsystems should be configured to implement this requirement？（）

• A、WebSphere MQ
• B、WebSphere Commerce Accelerator
• C、WebSphere Personalization
• D、Messaging
• E、Tivoli Policy Director