Corporations may issue which of the following bonds?
I. Equipment trust bonds
II. Double-barreled bonds
III. Mortgage bonds
IV. Revenue bonds

Corporations may issue unsecured bonds, such as debentures, subordinated debentures, and income bonds, or secured bonds such as mortgage bonds, equipment trust bonds, income bonds and guaranteed bonds. However, double-barreled bonds and revenue bonds are types of bonds issued by municipalities.