Which of the following MOST influenced the growth in the human population over the last century?
(A) Farmers have developed new crops that can grow in various climates and with small nutrient input.
Mechanical and chemical technologies have been developed to greatly increase agricultural production.
(C) The development of chemical fertilizers has enabled farmers to grow more intensive staple crops.
(D) Access to new freshwater resources has greatly expanded the use and efficiency of irrigation systems.