Pretty sure it’s A since they started their own reform
Anasazi
They built their dwellings around mounds in order to make it easier to see the enemy coming from any direction. Such constructions also aimed to slow down an enemy attack by making it hard to attack given that they had to march uphill.
Ice sheets reflect sunlight, warning Earth and causing more ice to melt, since this warmth is reflected into the ice sheets and glaciers themselves, which melt due to the increase in heat.
Glaciers shaped much of the landscape along North European Plain
In general, an economic recession refers to when a country or state is undergoing a period of slow economic growth (sometimes the growth is negative). It is less severe than a depression.