27. Based on the concept of supply and demand driving changes in the cost of money (interest rates), w of the following changes in the economy will tend to increase interest rates? a. Investors have decided to save a higher percentage of their income. b. Business in general is finding fewer opportunities to expand their operations. c. Investors are insecure about the economy d. Both b. and c. will tend to increase interest rates. e. All of the above will tend to increase interest rates