You are the administrator of the Windows XP Professional portable computers that are used by your company's sales representatives. The computers are members of a Windows 2000 domain. A Windows 2000 Server computer named Server1 contains the sales data used by the sales representatives in a shared folder named Data. When sales representatives travel, they use the Offline Files feature to access the files in the //Server1/Data shared folder. You want to ensure that the offline files on the portable computers are not accessible by unauthorized persons, in the event that a portable computer is lost. What should you do?（） 

• A、Instruct the sales representatives to configure the permissions on the offline files on their portable computers to allow access for only their user accounts. 
• B、On Server1, configure the permissions on all files in the Data shared folder to allow access for only the sales representatives. 
• C、Use a Group Policy object (GPO) to enable the Encrypt the Offline Files cache option for the portable computers. 
• D、On the portable computers, enable encryption of the %systemroot%/CSC folder.
• E、Apply this setting to the folder and files in the CSC folder.
• F、On Server1, encrypt all files in the Data shared folder.