According to Modigliani and Miller, if capital markets are efficient and there are no taxes, the managers' should________________________.

a. Actively manage their firms' capital structure to maximize value irrespective of adjustment costs

b. Actively manage their firms' capital structure to maximize value by trading off the adjustment costs and benefits of being at an optimal capital structure

c. Passively manage capital structure in the sense that they should not issue or buyback securities only to adjust capital structure. However, if they need external finance, they have to diligently choose between debt and equity

d. not take capital structure into account while making decisions