What Does the Producer Price Index (PPI)measure

What does the producer price index (PPI) measure?

A) The average change in the prices paid for all goods produced in the economy over a given year.
B) The average of the prices received by producers of goods and services at all stages of the production process.
C) The level of production of goods and services generated in the economy in a given year.
D) The difference between the prices consumers pay for goods and services and the prices producers pay for goods and services.