The Consumer Price Index (CPI) is a measure of the:

a. cost of a market basket of consumer goods and services relative to its cost in a base year.
b. change in the average price of a market basket of necessary goods and services
c. cost of a market basket of consumer goods relative to the previous year.
d. change in the average price of all intermediate goods and services.
e. average price of all final goods and services relative to the average price in the previous year.

a