Real GDP is a better measure of welfare than nominal GDP because: O a. nominal GDP includes only tangible goods, while real GDP also includes intangible output such as consulting services O b. real GDP includes foreign production by domestic firms, but nominal GDP does not O c. nominal GDP double-counts intermediate goods, while real GDP counts only final goods O d. nominal GDP rises with inflation, but real GDP does not O e. nominal GDP is what could be produced if production were perfectly efficient, whereas real GDP is a measure of what is actually produced