Which of the following is true?

a) CPI takes into account that the consumption basket changes in response to changes in relative prices.

b) If the number of unemployed is 5 million and the adult (civilian noninstitutional) population is 100 million, then the unemployment rate is 5%.

c) If consumption is an increasing function of disposable income and a decreasing function of the real interest rate, then an INCREASE in the incentives to invest will DECREASE the equilibrium real interest rate in a closed economy.

d) A $10 billion increase in tax revenue will increase national saving by less than $10 billion.