Answer: b) left; increases.
Explanation:
When there is public dissaving, the supply of loanable funds shifts to the left, and the real interest rate (r) increases.
Loanable funds are made available by people depositing their money for saving in the bank. If people therefore reduce their saving, the supply of loanable funds will reduce and the curve will therefore shift left.
As a result of this left shift/ reduction in supply, interest rates will have to increase to reflect the relative scarcity of the loanable funds.
