When using the cost of debt, the relevant number is the:
A.
pre-tax cost of debt, since most corporations pay taxes at the same tax rate.
B.
pre-tax cost of debt, since it is the actual rate the firm is paying bondholders.
C.
post-tax cost of debt, since dividends are tax deductible.
D.
post-tax cost of debt, since interest is tax deductible.