<em>Country D has crude oil reserves and also exports gold and grain</em> is the correct answer.
Explanation:
Economic diversification is the process in which an economy is shifted from as a single source of income to multiple sources by developing sectors and markets. It is the strategy for encouraging positive economic development.
An economy that has a broad spectrum of economic sectors is known as a diversified economy. For example, the US economy is diversified. It has natural resources, strong industries, and well-developed service sectors. The Brazilian and Russian economies are not considered to be diversified economies as both depend on natural resources and the defense industry only. Similarly, Exports are the major economic activity in the Brazilian economy.
