Answer:
c used goods were included in the GDP calculation
Explanation:
Gross domestic product is the sum of all final goods and services produced in an economy within a given period which is usually a year.
GDP calculated using the expenditure approach = Consumption spending + Investment spending + Government Spending + Net Export
If used goods are included in the calculation of GDP, it would be double counting because the good would have been included in the calculation of GDP when it was newly produced.
I hope my answer helps you
