Final answer:
Output and the real interest rate are determined by the intersection of the Investment-Savings (IS) and Liquidity preference-Money supply (LM) curves when the economy isn't in general equilibrium, making d the correct answer.
Step-by-step explanation:
If the economy is not in general equilibrium, output and the real interest rate are determined by the point at which the IS (Investment-Savings) curve and the LM (Liquidity preference-Money supply) curves intersect. Group letter d is the correct answer. The IS curve represents equilibrium in the goods market, and the LM curve represents equilibrium in the money market.
When these two curves intersect, it signals an equilibrium where both the money market and the goods market are in balance. This is not the same as general equilibrium which would also require the labor market to be in balance, represented in economic models by the FE (Full Employment) line. The point of intersection between the IS and LM curves indicates the level of real GDP and real interest rate at which the economy currently operates, even if not all markets are in equilibrium.