Wild Ducks Unlimited Wants to Have a Weighted Average Cost

Wild Ducks Unlimited wants to have a weighted average cost of capital of 8.5 percent. The firm has an after-tax cost of debt of 4.6 percent and a cost of equity of 12 percent. What debt-equity ratio is
Needed for the firm to achieve the targeted weighted average cost of capital?

A) .66
B) .72
C) .77
D) .84
E) .90