Final answer:
Economists measure economic growth by the percentage change in real, inflation-adjusted gross domestic product (GDP). GDP changes are direct indicators of an economy's health and standard of living. The correct answer to the question is C) Gross Domestic Product (GDP) changes.
Step-by-step explanation:
Economic Growth Measurement
Economists typically measure economic growth by tracking the percentage change in real (inflation-adjusted) gross domestic product (GDP). This method is a reflection of the economy's overall health and is commonly used to determine changes in the standard of living within a country. GDP changes signify the value of all goods and services produced within the country over a certain period, usually a year, adjusted for inflation. A growth rate of over 3% annually is often considered satisfactory to indicate a growing economy.
While population density changes, stock market volatility, and average rainfall patterns may affect an economy indirectly, they are not direct measures of economic growth. Therefore, the correct answer to the given question is C) Gross Domestic Product (GDP) changes.