The Concept of a Price Index Is That

The concept of a price index is that:

A) it is a measure of how the items included in the typical basket of goods have changed over time; it also includes price changes over time.
B) it is a measure of how the items included in the typical basket of goods have changed over time, while holding price changes constant.
C) it is a measure of how the prices included in the typical basket of goods have changed over time, holding the items in the consumption bundle constant.
D) it is an index of how much gasoline prices have increased, because all prices follow the price of gasoline.
E) it is an index of how much housing prices have changed, because housing is the most important item in the consumption bundle.