Which of the following statements is incorrect?

a) For stockholders, dividends and cash from selling the stock to other investors are the two sources of future cash flow

b) Based on the dividend discount valuation model (DDM), the current stock price is equal to all future dividends discounted by the cost of equity capital

c) The dividend discount valuation model (DDM) can be applied to any companies

d) Different types of payoff should be discounted using different types of cost of capital