Diego expects the market interest rate will keep decreasing in the future. Which of the following bond would give him the highest return based on his expectation?

Select one:

a. A 5-year 10% coupon bond

b. A 20-year 5% coupon bond

c. A 3-year zero coupon bond

d. A 30-year zero coupon bond

e. A 2-year 10% coupon bond