The Supply of Loanable Funds Curve Has a Positive Slope

The supply of loanable funds curve has a positive slope because the

A) higher the real interest rate, the lower the return to saving.
B) average return in the stock market is directly related to the real interest rate.
C) lower the real interest rate, the higher the return to saving.
D) lower the real interest rate, the lower the return to saving.
E) quantity of investment increases when the real interest rate increases.