Match the type of levelling with its application.
| Type of levelling | Process | ||
| 1. | Simple levelling | A. | When the differential levelling is done in order to connect a benchmark to the starting point of the alignment of project |
| 2. | Differential levelling | B. | When the difference of level between two points is determined by setting the level instrument midway between two points |
| 3. | Fly levelling | C. | The process of taking levels transverse to the direction of longitudinal levelling |
| 4. | Cross-sectional levelling | D. | When the difference of elevation between the points is large and there are obstacles between the points |
1
1-B; 2-C; 3-A; 4-D
2
1-B; 2-D; 3-A; 4-C
3
1-C; 2-D; 3-A; 4-B
4
1-B; 2-A; 3-D; 4-C