In a Cobb-Douglas economy, assume that real wages (W/P) grow at an average rate of 3% per year. Which of the following variables should also have an average growth rate of 3% per year? A.) Average labor productivity (Y/L). B.) The marginal product of labor (MPL). C.) Both (Y/L) and MPL will grow at 3% per year. D.) Neither (Y/L) nor MPL will grow at 3% per year.