Final answer:
Round Robin is the best scheduling policy for time-sharing operating systems, as it allows fair and efficient time allocation to multiple users by giving each active process a fixed time slice.
Therefore, the correct answer is: option B). Round robin
Step-by-step explanation:
In time-sharing systems, it is essential to allow multiple users to access the system simultaneously, and Round Robin facilitates this by giving each active process a fixed time slice (quantum).
This ensures that no single process monopolizes the CPU, leading to a fair distribution of processing time among all processes.
In contrast, policies like Shortest Job First, First Come First Serve, and Elevator (also known as the SCAN algorithm, typically used for disk scheduling) are not designed with time-sharing in mind.
Shortest Job First can lead to starvation of longer tasks, First Come First Serve does not handle varying process times well, and Elevator is focused on optimizing seek time for hard drives rather than CPU time sharing.