18. Economists suggest that food supply can best be assured by a policy of a. self sufficiency b. encouraging imports c. focusing on export crops d. food security e. all of the above 19. The Green Revolution has not resulted in a. reduced food prices b. increased yields c. more irrigation d. more agricultural research e. The Green Revolution has resulted in all of the above. 20. Engel's law suggests that as income rises, the demand for food a. rises less than proportionately b. rises more than proportionately c. rises proportionately d. falls e. none of the above 21. Marketing boards were intended to a. buy crops from farmers b. import crops from other countries c. subsidize agriculture by incurring losses d. ensure that all food stayed in the country