Whenever a program is to be executed, it needs to be brought into the memory from disk, where it is residing. When the program needs to be swapped out to disk, again some time is required. For effective CPU utilization, the time quantum must be substantially greater than the context switch time.
Time required to transfer process from memory = 100K/1000K = 1/10 seconds = 100 milliseconds
Add avg. latency to process transfer time , it becomes 100 +8= 108 milliseconds for one way transfer between disk and memory for the given program. The time required two way transfer is 216 ms. Thus, for efficient CPU utilization, time quantum should be substantially greater than 216 ms. The acceptable answer from options is 2.048 sec.