Your network consists of a single Active Directory domain. All servers run Windows Server 2008 R2.   All client computers run Windows 7. Users store all of their files in their Documents folder. Many users store large files.   You plan to implement roaming user profiles for all users by using Group Policy.You need to recommend a solution that minimizes the amount of time it takes users to log on and log off of the computers that use the roaming user profiles. What should you recommend？（）

• A、Modify the Group Policy object （GPO） to include folder redirection.
• B、Modify the Group Policy object （GPO） to include Background Intelligent Transfer Service （BITS） settings.
• C、On the server that hosts the roaming user profiles， enable caching on the profiles share.  
• D、On any server， install and configure the Background Intelligent Transfer Service （BITS） server  extensions.