GEF

Unit 3  |  Primary Sustainability Issues 85 8. Which of the following farming practices poses the least risk in terms of natural resource use, human health, and surrounding ecosystems? a. Irrigation b. Pesticide use c. No-till farming d. Genetically modified crops 9. What percentage of Earth’s freshwater sources is available for drinking and other human uses? a. Less than 1 percent b. About 3 percent c. Between 30 and 40 percent d. More than 70 percent 10. Photovoltaic cells are a technology component of which form of energy? a. Solar energy b. Wind energy c. Hydropower d. Geothermal energy