The characteristic that best represents the grassland ecosystem is that it is well-suited for food production.
In fact, corn, rice and wheat, that make up half of the food eaten around the world in a year, are produced in grasslands. Cattle industry is also exploited in grasslands.
The first option, least biodiversity, is not correct, since the grassland vegetation is varied in height and form, including many species of wild plants. Many species of animals have also adapted to the conditions presented in this habitat.
The second option, the smallest amount of rainfall, is also incorrect. Although grasslands rainfall may fail to support a habitat like a forest, it is much more abundant than in the deserts. The annual precipitation in grasslands range from 600 mm and 1500 mm a year.