Which of the Following Statements Describes the Concept Behind Paravirtualization

Which of the following statements describes the concept behind paravirtualization?

A) Guest operating systems are modified to actively cooperate with the hypervisor in order to ease virtualization costs and gain better performance.
B) Instead of running full virtual machines, containers are used to separate distinct parts of one commonly shared operating system that appear as a virtual machine.
C) To avoid the need for virtualization, special security measures are taken to allow different applications to coexist on one physical machine.
D) Each operating system is trusted to use only those resources assigned to it, thereby eliminating the need of an additional virtualization layer.