When calculated correctly, the income approach and the expenditure approach should?

When calculated correctly, the income approach and the expenditure approach should measure the GROSS DOMESTIC PRODUCT or GDP.

The income approach measures the total income earned by the households in a nation within a year.

The expenditure approach measures the total expenses incurred in buying goods produced by a country within a year. 

I'm pretty sure it's c. extremely gradual but not 100% sure though.