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