The correct answer is: B. default bonds.
A default bond is a bond that has been issued by a corporation and is exposed to default risk. This means that there is a risk that the corporation will not be able to repay the bond, which would result in a loss for the bondholder.
A corporation bond is a bond that has been issued by a corporation. Corporations issue bonds to raise money, and the bonds are typically used to finance new projects or to refinance existing debt.
A risk bond is a bond that is exposed to some degree of risk. This could be due to the creditworthiness of the issuer, the interest rate environment, or other factors.
A zero risk bond is a bond that is not exposed to any risk. This is a theoretical concept, as there is no such thing as a truly risk-free investment.
In conclusion, the correct answer is: B. default bonds.