ABC Canada Corp finances its required capital through a variety of sources so as come with different cost of capitals. For debt it pays 10% interest, for preferred stocks, it pays 14% preference dividend. And the required rate of return of equity holders is 18%. The corporate tax rate for ABC is 40% and weighted average cost of capital is 12.4%. If you are evaluating a lease vs buying proposal, what should be the appropriate discount rate to be used in this case?

A.14%

B.10%

C.18%

D.12.4%

E. 6%