Which of the Following Is Correct

Which of the following is correct?

A) The large-scale growing of high-demand crops,such as soybean and rapeseed,has increased the risks associated with monoculture.
B) Half of the wheat acreage in the United States is planted with just 9 varieties.
C) Some researchers believe that the future in agriculture is to move away from the instability and unnaturalness of annual,monocultural cultivation,and model agriculture after natural ecosystems.
D) The National Plant Germplasm System has more than 500,000 seed samples,representing 8,000 species.
E) All of the above are correct.