please somebody help me answer this, the assignment is due in 1h

According to the trade-off theory, a firm's optimal capital structure: is the debt-equity ratio that exists at the point where the firm's weighted after- tax cost of debt is minimized. is the debt-equity ratio that results in the lowest possible weighted average cost of capital. exists when the debt-equity ratio is 0.50. is found by locating the mix of debt and equity which causes the earnings per share to equal exactly $1