A disk has 300 cylinders ( 0 to 299 ). If the initial position of the read-write head is at cylinder 101 , moving towards the higher end of the disk, calculate the total head movement following C_LOOK policy for the read request sequence: 123, 45, 197, 87, 250, 198, 280

1. A456
2. B450
3. C458
4. D445

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Correct answer: A. 456

Explanation

Moving up from 101: 123, 197, 198, 250, 280 (179 cylinders). Jump back to 45 (235), then 87 (42). Total = 456.