Question $4(2\mathrm{.}5$ points$)$

A price index for a certain period is:

a ratio of real GDP to nominal GDP of the period.

the cost of a market basket of goods and services in a base period divided by the cost of the same market basket in that period.

a comparison of real GDP in that period relative to another period.

the cost of a market basket of goods and services in that period divided by the cost of the same market basket in a base period.