请指出下列各句话中的“影”所遵从的物理规律，用以下物理规律前的字母填入相应的横线内：

（1）形影不离______；（2）湖光倒影______；（3）毕业合影______；（4）立竿见影______．

a．光的直线传播规律；b．光的反射规律；c．凸透镜成像规律．

Assume that the expected dividend growth rate (g) for a firm decreased from 5% to zero. Further, assume that the firm's cost of equity (k) and dividend payout ratio will maintain their historic levels. The firm's P/E ratio will most likely:（）

A. become undefined.

B. increase.

C. decrease.