The Southwestern Desert of the United States Has Very Hot

The southwestern desert of the United States has very hot temperatures, low precipitation, and high evaporation rates.The soil is alkaline and low in nutrients.These factors result in minimal plant growth and very few species, compared with, for example, the tropical rainforest.One result of this is that desert food webs tend to have, on average, fewer trophic levels than rainforests.This suggests that in deserts the length of a food web is likely limited by

A) net primary productivity.
B) top predators.
C) human activity.
D) nutrient levels.
E) types of species present.