Answer: Option (b) is correct.
Step-by-step explanation:
Real GDP is totally based on the base year price level. This means that base year price level remains the same over all the periods. Therefore, Real GDP is generally not affected by the changes occur in the price level. Hence, it only includes the changes in output.
Nominal GDP takes into account the effect of changes in the price level. Therefore, it is affected by the changes in the price level and it is also measured in current U.S dollars. Hence, it doesn't show the true value of the goods and services produced in a given year.