Which memory management technique could deal with the increasing memory needs with the LEAST VM performance impact?

Suppose you have an ESX Server system running virtualmachines, and their memory requirements are steadily rising.Which memory management technique could deal with the increasing memory needs with the LEAST VM performance impact?

A.
Swapping inside the virtual machines by their own operatingsystems

B.
Transparent page sharing by the VMkernel

C.
The balloon technique,as provided for a component of VMwaretools

D.
The VMkernel swapfile on aVMFS