You have an Active Directory domain named contoso.com.You have an Exchange Server 2010  organization that contains a Client Access server named CAS1.Users connect to CAS1 from the Internet by using mail.contoso.com.The organization contains the following mobile clients：  （1）Windows Mobile 5.0 （2）Windows Mobile 6.1  （3）Windows Mobile 6.5  You plan to install a certificate on CAS1.You need to ensure that all clients can connect to CAS1 from the Internet by using Exchange ActiveSync.Which name should you include in the certificate？（）

• A、contoso.com
• B、CAS1.contoso.com
• C、EAS.contoso.com
• D、mail.contoso.com