is the correct answer.
Virtualization can be defined as the process which allows simultaneous usage of more than one operating systems on a single system. Actually a virtual instance is ran on a system on layer which is abstract from original hardware. Virtual Machines are of much use now-a-days.
Sometimes it happens that the Operating System disables the Virtualization process by default so the Option B is correct one in this case. So user will have to enable the Virtualization option in order to overcome the problem.