In the Notation of the Book,K = (1 - $\lambda$ )K_l

In the notation of the book,K = (1 - $\lambda$ ) K_l + $\lambda$ (1 - $\tau$ ) i Which of the following are correct?

A) The debt-to-equity ratio is $\lambda$
B) The cost of equity capital for a levered firm is K_l
C) The after-tax cost of debt capital is i
D) All of the above