Which of the following events is likely to encourage a company to raise its target debt ratio, other things held constant?

Which of the following events is likely to encourage a company to raise its target debt ratio, other things held constant?a.An increase in the corporate tax rate.b.An increase in the personal tax rate.c.An increase in the company’s operating leverage.d.The Federal Reserve tightens interest rates in an effort to fight inflation.e.The company's stock price hits a new high.