At some point, rising income levels lead to demands for greater environmental protection and, as a result, pollution levels fall. A study by Grossman and Krueger found this generally occurred before per capita income levels reached Multiple choice question. $31,000. $25,000. $1,000. $8,000.Which statement accurately describes the global economy in the twenty-first century? Multiple choice question. More nations are refusing to adopt liberal economic policies. Globalization can limit a country's movement toward greater economic development. Barriers to the free flow of goods have been increasing. More nations are becoming part of the developed world