A firm's cost of debt often differs from the yield reported on its bonds because Select one: a the underwriting costs for new bond issues are not tax deductible, raising the cost of debt relative to bond yield O b. the cost of debt changes infrequently since bond rating agencies do not change their recommendations atten O c the interest paid on corporate bonds is tax deductible O d. speculators can drive the cost of debt down so that bond yields exceed it Oe the firm's cost of debt is unknown when the bonds are first sold