The Risk Structure of Interest Rates Refers to The

The risk structure of interest rates refers to the:

A) relationship among the interest rates of bonds with different maturities.
B) relationship among the interest rates of bonds from different issuers with the same maturities.
C) relationship among the interest rates of bonds from the same issuer but different maturities.
D) additional interest required to compensate the buyer for the longer maturity of the bond.