In economics, investment refers to the process of accumulating:

Of the following, which group has the fastest-growing population in the United States?

a. female heads of households b. male heads of households c. white heads of households d. black heads of households e. single people

The aggregate demand curve

a. represents the relationship between prices and quantities of all goods produced in an economy b. is derived from equilibrium conditions in the labor and money markets c. gives the equilibrium level of real GDP corresponding to a given price level d. is the sum of an economy's individual demand curves e. plots the interest rate as a function of output