Please answer and explain why please

Which of the following statements about the cost of capital is CORRECT? Select one: O a. Both the cost of debt and equity financing will decrease when the Federal Reserve tightens credit. Ob. The WACC of a firm will decrease when investors become more risk averse. O c. Both the cost of debt and equity financing will decrease when a nuclear plant company encounters a ban on nuclear power generation in certain states O d. Both the cost of debt and equity financing will decrease when a firm increases its debt/asset ratio. Both the cost of debt and equity financing will increase when a firm expands into a risky new area