Which of the following best describe the idea of limited direct execution?

Question $1$ options:

The CPU must be virtualized so that processes cannot execute privileged instructions in a non$-$privileged context. This is done by pretenting that those instructions do not exist in the user space and only execute NOP's.

A process must be able to use the system resources of CPU, memory and I$/$O without having complete control over the entire system, effectively overthrowing the operating system $-$ all while providing a mechanism for the OS to regain control from that process and grant the same privilege to another process.

It is the virtual address space $($q$.$v$.)$ which provided the operating system with the greatest facility to control processes in such a way as to grant and remove access to system resource on demand.

An operating system must be able to grant limited time to a process at which point it removes that process from the CPU and grants time to another process.