问题：

[单选]

You develop a Windows Communication Foundation (WCF) service that uses basic authentication for client credentials. This service is currently configured to use message security. The service is hosted on a server in workgroup mode.Users report that their passwords are stolen when they use public computers.You need to ensure that messages are secure and users are authenticated.You prevent the service from being called over HTTP through Microsoft Internet Information Services (IIS) configuration.
What should you do next?（）

A . Use the transport security mode and specify None for transport client credential type.
B . Use the transportWithMessageCredential security mode and specify Basic for the transport client credential type.
C . Use the message security mode and specify Basic for the transport client credential type.
D . Use the transportWithMessageCredential security mode and specify None for the transport client credential type.