单选题 An analyst does research about cost of capital. All else being equal, if a U. S. company's marginal tax rate decreases, the company's weighted average cost of capital will most likely:
A. decrease.
B. remain unchanged.
C. increase.

【正确答案】 C
【答案解析】[解析] 加权平均资本成本WACC=Wce×Kce+Wps×Kps+Wd×Kd×(1-t)。其中，Kce是普通股股东的必要回报率，Kps是优先股股东的必要回报率，Kd是公司发行新债券的必要收益率，所以税率t减小，WACC会增大。