In explaining the level of unemployment, Keynes emphasized,- O a. Changes in technology. O b. Inflationary expectations. O c. Lending by financial institutions. O d. Aggregate demand. In the Keynesian model: O a. Households only save and lend, and do not borrow. O b. Investment spending is highly sensitive to investors' confidence and expectations of future sales and profits O c. Consumption spending is more sensitive to the interest rate than to income. O d. Investment spending, especially in a recession, is highly sensitive to the interest rate.