Can the nominal interest rate available to an investor be negative? (Hint: Consider the interest rate earned from saving cash "under the mattress.")(Select the best choice below.)

A. The nominal interest rate can never be negative because the inflation rate is always negative.

B. The nominal interest rate can be negative when the inflation rate is positive.

C. The nominal interest rate can never be negative because investors can always earn 0% on their investments.

D. The nominal interest rate can be negative when the real rate of interest is negative.