单项选择题

A.Upgrade the memory to 1 GB of RAM.
B.Upgrade the hard disk to 120 GB with 40 GB of free space.
C.Install a video adapter that has 128 MB of RAM, support for Microsoft DirectX 9, and Microsoft Pixel Shader 2.0.
D.Install a video adapter that has 128 MB of RAM, support for Microsoft Scalable Link Interface (SLI) and Microsoft Pixel Shader 2.0.