Question

in top - down regulation, the size of a rabbit population is determined by:
the amount of food found in their habitat.
the biotic potential of female rabbits.
the number of foxes and coyotes in the area.
the severity of winter.

Explanation:

Top-down regulation of population size is controlled by predators (higher trophic levels). Foxes and coyotes are natural predators of rabbits, thus influencing their population.

Answer:

the number of foxes and coyotes in the area.