Your network contains a server named Server1 that runs Windows Server 2008 R2.
Server1 has the Remote Desktop Session Host (RD Session Host) role service installed.
You need to ensure that Remote Desktop users can use the user interface elements of Windows Aero.
What should you do on Server1?

A.
Change the display settings.

B.
Add the Desktop Experience feature.

C.
Install a DirectX 10 compliant video adapter.

D.
Add the Quality Windows Audio Video Experience feature.

Explanation:
When a user uses Remote Desktop Connection to connect to a Remote Desktop Session Host (RD Session Host) server, the desktop that exists on the RD Session Host server is reproduced, by default, in the remote session. To make the remote session look and feel more like the user’s local Windows 7 desktop experience, install the Desktop Experience feature on an RD Session Host server that is running Windows Server 2008 R2.
Desktop Experience installs components and features of Windows 7, such as Windows Media Player, Windows Defender, and Windows Calendar
Source: http://technet.microsoft.com/en-us/library/cc772567.aspx