We use the _________ to determine the purchasing power of income.

A. Interest rate.
B. Real GDP.
C. CPI.
D. GDP.
E. None of the above.

Check this site for your answer.

http://www.bls.gov/cpi/

cpi

To determine the purchasing power of income, we use the Consumer Price Index (CPI). The CPI is a measure of the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services. It helps to quantify the inflation rate and understand how much the cost of living has changed.

To find the answer to this question, you can visit the website provided (http://www.bls.gov/cpi/) and look for information related to the purchasing power of income. The Bureau of Labor Statistics (BLS) website offers data and resources on various economic indicators, including the CPI. By exploring the site, you can find the relevant information to confirm that the correct answer to the question is "C. CPI."