This event happened:
B. Settlers who wanted to farm migrated west to Oregon Country.
Explanation:
The Great Plains had been too dry to farm due to the climate that they offered as they could not support the extensive farming and had only been suitable for grass.
The settlers who had wanted to farm thus had to move away to lands they could use to farm.
The lands that they had picked thus were in Oregon county which became one of the most fertile regions of the whole area and was the bread basket of the region.
