<span>The answer is: at the level of population. A population is a group of organisms of the same species in an area. Here, we have a group of butterflies of the same species laying eggs on milkweed plants. Therefore, butterflies laying their eggs on milkweed plants occurs at the level of population. </span>
Answer:
B) Absence of native grasses
Explanation:
The grasses, which acted as a windbreak and whose roots anchored the soil in place, were overgrazed and/or removed to allow for farming. Once a few years of severe drought affected the area, any wind storm was able to blow the topsoil away, rendering the farm land of the Great Plains virtually unusable in many areas. Ground cover is an essential part of sustainable agriculture.
