If You Want to Increase Your Purchasing Power by Investing

If you want to increase your purchasing power by investing in a bond,then:

A) you must purchase that bond at a discount.
B) the nominal rate of return on that bond must be less than the inflation rate.
C) you should purchase a premium bond.
D) the nominal rate of return must equal or exceed the rate of inflation.
E) you must earn a positive real rate of return on that bond.