Answer:
b. ecosystems in a region, species in an ecosystem, and genes and alleles in a species.
Explanation:
Biodiversity has three levels - ecosystem, species and genetic diversity. Therefore, Biodiversity can be defined as the variability among living organisms involving terrestrial, marine, and other aquatic ecosystems, genes and alleles in a species and their ecological complexes such as diversity within species, and between species of the ecosystems.
