Fractional Crystallization
The Soil is less rich in minerals and other things that make good fields and better crops.
Option B. abyssal plains.
Hope it helps!
The pointy things that hang down from the cave's ceiling are stalactites. (A)
The pointy things that grow up from the cave's floor are stalagmites.
(I imagine wearing shorts and hiking through tall grass in the Summer, and I say to myself "When the Mites go up, the Tights have to come down.".)
