Round Robin scheduling policy is most suitable for a time-shared operating system.

Explanation:
A time-shared operating system is designed to support multiple users simultaneously by sharing the CPU time among them. Therefore, the scheduling policy for such an operating system should be efficient in terms of CPU utilization, fairness, and responsiveness.

Round Robin scheduling policy is a preemptive scheduling algorithm that is widely used in time-shared operating systems. In this policy, each process is given a fixed time slice called a time quantum. The CPU executes the process for the allotted time quantum and then switches to the next process in the queue. If a process completes its execution within the time quantum, it is removed from the queue. Otherwise, it is preempted, and the CPU is allocated to the next process.

Advantages of Round Robin scheduling policy:
- Fairness: This policy ensures that each process gets an equal amount of CPU time, regardless of its priority or length.
- Responsiveness: Since each process gets a time quantum, it can respond quickly to any input or event.
- Efficient CPU utilization: Round Robin policy ensures that the CPU is always busy executing a process, which leads to high CPU utilization.

Disadvantages of Round Robin scheduling policy:
- Overhead: There is some overhead involved in context switching, which can affect the overall performance of the system.
- Long waiting time: If the time quantum is too long, some processes may have to wait for a long time before getting CPU time. On the other hand, if the time quantum is too short, there may be too much context switching, leading to overhead.