A technician upgrades a computer from Windows XP Media Center Edition to Windows Vista Home Premium. After the upgrade Aero will not turn on. The system has a 2.4 GHz processor, 1GB of RAM, and a DirectX 7 video card. Which of the following will resolve this issue?（）

A. Aero cannot be used on Windows Vista Home Premium.
B. Upgrade the video card to a DirectX 9 compatible card.
C. Upgrade the video driver.
D. Upgrade the RAM to 4GB