You deploy a mobile messaging solution by using front-end and back-end servers that run Microsoft Exchange Server 2003 Service Pack 2. Certificates are installed on all Microsoft Windows Mobilebased devices. You need to allow devices that run Microsoft Windows Mobile 5.0 to perform certificate-based authentication for Microsoft Exchange ActiveSync. What should you do？（）
- AConfigure the front-end server for Kerberos Constrained Delegation （KCD）.
- BConfigure a Routing Group Connector between the front-end and back-end servers.
- CConfigure the Windows Mobilebased devices with a Point-to-Point Protocol （PPTP） connection.
- DConfigure the Windows Mobilebased devices to use Extensible Authentication Protocol （EAP） and either a smart card or a certificate.