The answer is C. Mortgage bond.
A mortgage bond is a type of bond that is secured by a mortgage on specific assets of the issuing corporation. This means that if the corporation defaults on the bond, the bondholders have the right to foreclose on the mortgaged assets and sell them to repay the debt.
Registered bonds are bonds that are registered in the name of the owner. This means that the bondholder’s name is recorded on the bond’s registry, and the bond can only be transferred by endorsement.
Collateral trust bonds are bonds that are secured by a pledge of certain assets of the issuing corporation, such as stocks or bonds of other companies.
Debenture bonds are bonds that are not secured by any specific assets of the issuing corporation. This means that if the corporation defaults on the bond, the bondholders have no recourse to the corporation’s assets.
In conclusion, the correct answer is C. Mortgage bond.