In a levelling work the following readings were taken with a dumpy level as 2.05, 0.525, 1.875, 1.21, 3.245, 1.94, 0.975, 2.875 (in m units). If the instrument was shifted after the second and fifth readings, the readings recorded in the foresight column is:
1
0.525, 3.245, 2.875
2
0.525, 1.94, 2.875
3
2.05, 1.875, 1.94
4
1.875, 1.94, 2.875