Answer:
d. sinking fund.
Explanation:
A bond refers to a debt or fixed investment security, in which a bondholder (creditor or investor) loans an amount of money to the bond issuer (government or corporations) for a specific period of time.
Generally, the bond issuer is expected to return the principal at maturity with an agreed upon interest to the bondholder, which is payable at fixed intervals.
A sinking fund is a provision of a bond indenture which is designed to ease the burden of principal repayment by spreading it out over several years.
Hence, a sinking fund is generally viewed or assumed to protect the bondholders such as creditors or investors because the fund set aside would serve as a collateral incase the bond issuer can't pay in the future.
