Answer:
Poverty and lack of building materials, is the correct answer.
Step-by-step explanation:
The Sod houses were used by the settlers in the plains of United States and Canada. It was used for animal shelters. The sod houses were constructed as the standard building materials such as wood and stones were not available in the prairies. The first settlers were poor so instead of purchasing construction materials they used prairie grass for constructing the houses. Prairie grass is long and have thick roots. The patches of grasses were used in building the walls and these houses were vulnerable to rain damage.