Biodiversity encompasses the number of: a. ecosystems in a region and number of species in the ecosystem. b. ecosystems in a region, species in an ecosystem, and genes and alleles in a species. c. ecosystems in a region. d. species present in an ecosystem. e. genes and alleles in a species.

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.