64-bit CPUs are supported for VMotion in VirtualCenter 2.0

A.
only when migrating 32-bit Guest OSes.

B.
when migrating either 32-bit or 64-bit Guest OSes, so long as the Nx flag is hidden.

C.
when migrating either 32-bit or 64-bit Guest OSes, regardless of CPU compatibility

D.
when migrating either 32-bit or 64-bit Guest OSes, so long as the VMware CPU Compatibility Tool detects two compatible CPUs.