9. If nominal GDP and real GDP both rise by 10 percent , then the GDP deflator a. also rises by 10 percent. b. rises by about 20 percent. c. falls by 10 percent. d. is unchanged

The correct answer is d. is unchanged.<br /><br />Explanation:<br /><br />The GDP deflator is a measure of the price level of all final goods and services produced in an economy. It is calculated as the ratio of nominal GDP to real GDP:<br /><br />GDP deflator = Nominal GDP / Real GDP<br /><br />If both nominal GDP and real GDP rise by 10 percent, then the GDP deflator remains unchanged. This is because the 10 percent increase in nominal GDP is exactly offset by the 10 percent increase in real GDP, leaving the ratio (and thus the GDP deflator) unchanged.<br /><br />Therefore, the correct answer is d. is unchanged.