A bank has requested proposals for a storage solution to upgrade their disaster recovery processes for their IBM System z， UNIX， and Microsoft Windows environment. The solution must simulate a multi-site environment and provide the customer the ability to evaluate Metro Mirror， Global Mirror， Global Mirror for z/OS， and FlashCopy. Floor space is limited.  Which solution best meets the specified requirements（）

• A、two IBM System Storage DS8100 systems
• B、one IBM System Storage DS8300 with LPAR
• C、two IBM System Storage DS6800 systems in a single rack
• D、one IBM System Storage DS6800