c. number and variety of organisms vs. changing environment
Explanation:
In an ecosystem populations are in dynamic equilibrium with each other, for when a population decreases the population of its predators also decreases, because the various populations are dependent on each other for survival. What we can understand from this is that the diminishing population of a species has caused a change in the environment, making that environment unsuitable for the predator population.
In other words, dynamic equilibrium occurs when the size of a population of a species varies with changes in the environment in which they live. For this reason we can state that the number and variety of organisms vs. changing environment best indicates the dynamic balance of an ecosystem.
She should have to classify this animal under pseudocoelomates category. The body cavity of these animals are filled with fluids. Internal organs are covered by the fluid filled space. The body cavity serves as the hydrostatic skeleton and have other functions such as digestion of food and waste removal.
