The hardships faced by the settlers on the Great Plains were numerous and at times, devastating.
The options given for this question are prairie fires, flooding, a surplus of trees, and loose soil. Let's analyze each of these options to find the correct answer:
a. Prairie fires: The Great Plains, which stretch across the central United States, were covered in expansive grasslands and prairies. Dry conditions, particularly during periods of extreme heat or drought, would leave these regions susceptible to prairie fires. These fires could destroy crops, homes, and other important resources for the settlers living there, posing a significant challenge for survival and economic stability.
b. Flooding: While flooding can happen in any area given the right conditions, it was less common in the Great Plains. This is due to the topography and vegetation of the region which usually does not favor accumulation of water from rainfalls or melting ice.
c. Too many trees: The Great Plains had very few trees. This could be considered a challenge as trees provide wood for building, fuel, and could offer protection from the elements. But, it was not a hardship directly because of their abundance, rather their scarcity.
d. Loose soil: One might think that loose soil would make farming difficult, but in fact, it was actually beneficial for farming. The loose, rich soil of the Great Plains was ideal for planting crops and was one of the factors that attracted settlers to the region in the first place.
Given this analysis, it's clear that the hardship faced by settlers on the Great Plains referenced in this question is a. Prairie fires.