Match the shaft sinking method with its applicability.
| Shaft sinking method | Applicability |
|---|
| (P) Piling system | (1) Strata consisting of alternate strong and loose soil, and drum sinks down by its own weight |
| (Q) Caisson method | (2) Sinking through the loose ground near the surface |
| (R) Cementation | (3) Heavily watery strata, including quick sand |
| (S) Freezing | (4) Fissured water bearing strata without running sand |