9. The phrase, a sustained increase in the average level of prices of goods and services in an economy over time, describes which of the following terms? A. Deflation B. Inflation C. Disinflation D. Economic growth

The correct answer is B. Inflation.<br /><br />Inflation refers to a sustained increase in the average level of prices of goods and services in an economy over time. It means that the purchasing power of money decreases, and the same amount of money can buy fewer goods and services than it could before. Inflation is typically measured using price indices, such as the Consumer Price Index (CPI) or the Producer Price Index (PPI).<br /><br />Option A, Deflation, is the opposite of inflation. It refers to a sustained decrease in the average level of prices of goods and services in an economy over time.<br /><br />Option C, Disinflation, refers to a decrease in the rate of inflation. It means that the inflation rate is still positive but is decreasing.<br /><br />Option D, Economic growth, refers to an increase in the production of goods and services in an economy over time. It is typically measured by the growth in Gross Domestic Product (GDP).<br /><br />Therefore, the phrase "a sustained increase in the average level of prices of goods and services in an economy over time" describes inflation.