Given the All-Equity Cost of Capital,the Cost of Levered Equity

Given the all-equity cost of capital,the cost of levered equity can be computed as:

A) R_S = (B/S) (R₀) + (1 − t_C) B.
B) R_S = R₀ + (B/S) (1 − t_C) (R₀ − R_B) .
C) R_S = R₀ + (1 − t_C) B.
D) R₀ = R_s + (B/S) (1 − t_C) (R₀ − R_B) .
E) R₀ = R_s + (1 − t_C) B.