What change must be made to the Guest OS kernel to support paravirtualization?

What change must be made to the Guest OS kernel to support paravirtualization?

A.
None; the unmodified Guest OS kernel communicates with the CPU through an emulated CPU which is provided by the hypervisor.

B.
The Guest OS kernel must replace privileged CPU instructions with calls to the hypervisor.

C.
None; the unmodified Guest OS kernel can communicate directly with the hardware CPU.

D.
The Guest OS kernel must rewrite modules to communicate with the hypervisor.