All of the following methods are correct except:

Like debt and preferred stock, cash flows from common equity are fixed.

Firms have two sources of common equity, retained earnings and new stock issues, and thus two costs of common equity.

From the shareholders' perspective, the opportunity cost of retained earnings is the return the shareholders could earn by investing the funds in assets whose risk is similar to that of the firm.

If the firm cannot invest its retained earnings to achieve a sufficient risk-adjusted return, shareholders would be better off receiving 100 percent of its net income as dividends.