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 low and bond when interest rates are high.
B) a firm will want to take advantage of timing its fund raising in order to maximize costs over the long run.
C) the market allows no leeway in the debt to equity ratio before penalizing the firm with a higher cost of capital.
D) a company will sell bonds when interest rates are low and stock prices are high.