Assume a closed economy with government in the long run. Why does NS curve slope up? (Hint: formula is your friend, and so is a graph). O a. None of the answers offered are accurate. O b. If real interest rate is higher, people are more rewarded for giving up their current consumption (private savings goes up, so national savings goes up as well.) O c. If real interest rates go up, government spending goes down. O d. If real interest rates go up, firms invest less. O e. Trick question: it slopes down