Question

A variety of different mechanisms in nature help create diversity in organism populations. The tundra found in the northernmost parts of the planet is the world’s youngest biome. The tundra is home to a variety of plants and animals. Organisms that can be found in the tundra include shrubs, mosses, caribou, polar bears, and wolves. Which mechanism do the different organism populations found across the tundra exemplify?

genetic diversity
ecosystem diversity
species diversity
variation

Answer 1

Species diversity.

Those examples (shrubs, mosses, caribou, polar bears, wolves) are different species living in the tundra — that variety of species is species diversity. Genetic diversity refers to variation within a species, ecosystem diversity to different habitats or ecosystems, and "variation" is too general.