You deploy a mobile messaging solution with Microsoft Exchange Server 2003 Service Pack 2.   When the application is running， it must not be able to access protected registry keys.   You need to ensure that the application meets the outlined requirement. What are two possible ways to achieve this goal？（）

• A、Use Microsoft Windows Mobile 5.0 Pocket PC Phone Edition operating system.
• B、Use Microsoft Windows Mobile 2003 for Pocket PC operating system.
• C、Use Microsoft Windows Mobile 5.0 for Smartphone operating system.
• D、Use Microsoft Windows Mobile 2003 for Smartphone operating system.