What is the difference between a nominal variable and a real variable?
a. Nominal variables are economic variables that are adjusted for inflation, whereas real variables are not.
b. Nominal variables are non-monetary variables, whereas real variables are monetary variables.
c. Nominal variables are measured in current prices, whereas real variables are adjusted for changes in price levels.
d. Nominal variables are qualitative variables, whereas real variables are quantitative variables.

The correct answer is: c. Nominal variables are measured in current prices, whereas real variables are adjusted for changes in price levels.