Question 3 (1 points): Without preemption, shortest job first does not minimize mean turnaround time. In fact, in some corner cases, it fails to even achieve the minimum mean turnaround time possible without preemption (and on a single core). One reason for this is that the shortest job first does not consider schedules that leave the processor idle in order to wait for a short job. Which of the following are examples of such scenarios? Select all that apply A. thread A becomes runnable at time 0, requires 5 units of time; thread B at time 2 requiring 2 units of time B. thread A becomes runnable at time 0, requires 10 units of time; thread B at time 5 requiring 9 unit of time C. thread A becomes runnable at time 0, requires 5 units of time; thread B at time 1 requiring 2 units of time D. thread A becomes runnable at time 0, requires 5 units of time; thread B at time 1 requiring 4 units of time