If a corporate bond is callable, this means that: A. the issuing corporation can buy the bond back from the bondholder, and the bondholder cannot refuse to sell. B. all else being equal, the callable bond is riskier to the bondholder than an equivalent non-callable bond. C. all else being equal, the callable bond is less risky to the bondholder than an equivalend non-callable bond. D. both A and B are true. E. both A and C are true