The most important factor that determines where major ecosystems are located on the globe is

A) soil type.
B) available vegetation.
C) climate.
D) oxygen levels.
E) political boundaries.

Climate is the most important factor that determines where major ecosystems are located on the globe. Climate includes factors such as temperature, precipitation, and seasonal variations, which all play a significant role in shaping the characteristics of plant and animal communities in an ecosystem. Soil type, available vegetation, oxygen levels, and political boundaries may also influence ecosystem distribution, but they are secondary factors that are often shaped by climate.