Saguaro cacti, elf owls, horned lizards, and fire ants all share the same area of desert. Which of the following groups is a population?
A- all of the plants growing in that area of desert
B- all of the elf owls, horned lizards, and fire ants living in that area of the desert
C- all of the fire ants living in that area of the desert
D- all of the species living in that area of the desert