问题如下：
Company M is going to issue new debt, which lead the company’s WACC rising from 10% to 15%. Which of the following is correct?
选项：
A.The cost of debt is larger than the cost of equity.
B.The company’s prospects are improving.
C.The company is beyond the optimal capital range.
解释：
C is correct.
考点：Capital Structure Theory: with tax
解析：由于负债的增加导致公司加权平均资本成本的上升，举债带来的财务困境成本超过了举债带来的收益，此时公司已经偏离了最优的资本结构。
看到很多之前的同学问B为什么不对，助教说修改了答案。想问下是修改了什么？
现在B的选项是对的吗，如果不对，为什么？
