How do macroeconomists distinguish between nominal and real values of​ variables?
a. real variables are always adjusted to reflect seasonal variation while nominal variables are not.
b. nominal variables are always adjusted to reflect seasonal variation while real variables are not.
c. nominal variables are measured in market​ prices; real variables are measured in quantities of goods and services.
d. nominal variables are measured in quantities of goods and​ services; real variables are measured in market prices because that is how they are really counted?