A corporation that uses both debt and equity in its capital structure has concluded that the risk premium it must pay on its common stock is too high. To decrease this, the firm can $$

A$.$ increase the proportion of short$-$term debt to decrease the cost of capital

B$.$ increase the proportion of long $-$ term debt to decrease the cost of capital

C$.$ decrease the proportion of common stock equity to decrease financial risk

D$.$ increase the proportion of common stock equity to decrease financial risk