Answer: b) the par value of the bond.
Upon maturation, the carrying value of a bond will always be equivalent to the par value of the said bond.
The carrying value of a bond is also known as the face value of the bond, or the sum of the premiums that have not been wiped out and the par value of the bond
When the bond matures, the discounts and premiums will be wiped out or amortized, and then the par value of the bond will remain.