A，B，C三种零件，其中B种零件300个，C种零件200个，采用分层抽样方法抽取一个容量为45的样本，A种零件被抽取20个，C种零件被抽取10个，三种零件总共有______个．

A stock has a required rate of return of 15%, a constant growth rate of 10%, and a dividend payout ratio of 45%. The stock's price-earnings ratio should be:（）

A. 3.0 times.

B. 9.0 times.

C. 4.5 times.