When studying changes in the economy over time, economists want a measure of the total quantity of goods and services the economy is producing that is not affected by changes in the prices of those goods and services. In other words, economists want to study

a. nominal GDP.

b. real GDP.

c. the GDP deflator.

d. GNP.

b. real GDP.

Explanation:

Real GDP is a measure of total goods and services produced by an economy that is adjusted for changes in price.

Nominal or monetary value is expressed as an index of total output.

Economics prefer to study real GDP as this is not affected by inflationary changes and gives more accurate estimate of the state of the economy.