单选题：Suppose that a disk drive has 200 tracks, numbered 1 to 200. The

Suppose that a disk drive has 200 tracks, numbered 1 to 200. The drive is currently serving a request at cylinder 100, and the previous request was at a cylinder smaller than 100. The queue of pending requests, in arrival order, is 50,60,40,20,90,160,150.
What is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for SSTF? @[D](1)
A. 220
B. 200
C. 240
D. 210




A.220
B.200
C.240
D.210


答案：D