1. In the 1920s, over 25 million acres of the American southern plains were stripped of prairie grasses to provide more land for farmers to grow wheat. The prairie grasses had served to hold the soil in place and prevent erosion. In the early 1930s, a series of severe dust storms eroded topsoil from more than 13 million acres of the southern plains and dumped it as tons of dust particles over many cities in the Northeast. Farmland was destroyed and people were sickened from "dust pneumonia." This occurrence illustrates that A. farmers should never clear land to grow crops as it always creates problems B. once an ecosystem has been altered, it can not be restored to normal C. the farmers deliberately altered the equilibrium of the cities in the Northeast D. when humans alter ecosystems, serious consequences may result​