In Order to Determine the Economy's Real GDP Growth Rate

In order to determine the economy's real GDP growth rate between two time periods,we should look at

A) nominal national income,because it compares actual output in each time period.
B) real national income in each time period,which is equal to nominal national income corrected for price-level changes.
C) potential national income,corrected for price-level changes.
D) real national income in each period,which is equal to nominal national income corrected for quantity changes.
E) only the real national product from the latest time period.