A Firm's Debt to Equity Ratio Varies at Times Because

A firm's debt to equity ratio varies at times because

A) a firm will want to sell common stock when prices are high and bond when interest rates are low.
B) a firm will want to take advantage of timing its fund raising in order to minimize costs over the long run.
C) the market allows some leeway in the debt to equity ratio before penalizing the firm with a higher cost of capital.
D) all of the other answers are correct.