Which of the following can reduce biodiversity within a natural environment? a. yucca moths pollinate and feed on yucca plants in the mojave desert. b. red-billed oxpeckers eat ticks off of impalas' coats in the grasslands of east africa. c. non-native american bullfrogs out-compete native amphibians in the tropical andes. d. giant kangaroo rats enrich the soil for plants with their piles of grass clippings in the california grasslands.