Answer:
The correct answer is when the slope is steep.
Step-by-step explanation:
The advancement of water inland is dependent on the rate at which water wears off the continental shelf and the coastal plain. The higher the amount of rainfall, and the harshness of the dry spells, the faster the rate of erosion that occurs at the coastal plain.
As the erosion increases, the coastal plain becomes steeper. The steeper the plain, the water flowing erodes the coastal plain at a faster rate. Hence the water advances farther inland faster than where the slope is gentle or gradual.
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