Answer:
Option (a) is correct.
Step-by-step explanation:
Real balance effect: This effect states the relationship between the price level and the purchasing power of the consumer. If there is a higher price level in an economy then this will reduce the purchasing power of the consumers and results in a fall in investment expenditure, net exports and consumption expenditure. That's why aggregate demand curve is slopes downward.
Interest-rate effect: This effect states the cost of borrowing funds with the price inflation in an economy. If there is a higher interest rate then most of the consumers cut down there borrowings activities which is one of the reason of downward sloping demand curve.
Foreign purchases effect: When there is a fall in the price level then as a result the price in the United states falls relative to the foreign prices. Hence, there is an increase in the U.S exports and decrease in the U.S imports.