What is the correct response to the VM management team?

The organization you work for is currently running vSphere 4.1 U1. Your team have just created a new Test/ Dev environment based on vSphere 5. The VM management team have asked if you could combine the curret 4.1 U1 environment and 5.0 vCenters with Linked-Mode. What is the correct response to the VM management team?

A.
additional licensing is required to use Linked-Mode

B.
only vCenter administrators can use Linked-Mode

C.
No problem

D.
vCenter 4.1 and vCenter 5 cannot be joined with Linked-Mode