Answer:
b. Face value plus unamortized premium
Explanation:
When bonds are sold for more than their face value, such bonds are to be sold on premium. Mean that the in addition to the face value, an unamortized premium has been paid.
Such cases arises when the coupon payments made by bond are greater than the market rates.
Example: Let's say Samsung issues bonds at 10% coupon rate for 5 years bond while the market rate for the same 5 year bond is 8%. The Samsung is said to have sold the bond on premium.