Why can minerals that form early in fractional crystallization grow distinct crystal shapes?

The correct answer is - B. Agriculture in Nebraska changes the local landscape.

The agriculture is not a natural process, but it is a human activity. The human kind started to perform agriculture during the Neolithic period, and since than has been contributing to large scale erosion and change in the appearance of the landscape all around the world.

The agriculture contributes in multiple ways for an increased erosion. The plowing, is good for the crops, but it loosens the soil, thus making it more vulnerable to erosion. The irrigation contributes to erosion with the water taking the surface layers away from their original position. And also, the pesticides are damaging the soil, destroying its natural structure, and make it easy to erode.