In the semi-arid region of the Karst Plateau, geologists have long monitored the sudden collapse of surface soil, a phenomenon locally known as "swallow holes." While subterranean water flow is the primary long-term driver of this geological erosion, the immediate trigger for these sudden cave-ins is often human activity. Specifically, during the agricultural expansion of the 1970s, farmers installed extensive underground drainage pipes to redirect seasonal runoff away from their crops. This concentrated redirection of water significantly increased the local water pressure against the delicate limestone ceiling of the underground caverns. Consequently, the structural integrity of the limestone weakened rapidly, culminating in the widespread collapses observed today. Although some local residents attributed the cave-ins to recent seismic tremors, geological sensors recorded no significant tectonic activity during the major collapse events. Instead, the data confirmed that the redirecting of surface runoff was the direct catalyst for the structural failures.
According to the passage, the immediate trigger for the sudden collapse of surface soil in the Karst Plateau was which of the following events?
- the concentrated redirection of seasonal runoff through underground drainage pipesCevap
- Bthe natural long-term erosion of the limestone ceiling by subterranean water flow
- Cthe pressure of collapsing surface soil forcing runoff into the underground caverns
- Drecent seismic tremors and tectonic shifts occurring along the plateau