----- How about the book you are reading now?

----- Excellent indeed. You can find many problems we have come across _____ in it.

A．covered

B．covering

C．are referred

D．referred

从国内速递市场看，邮政速递仍占绝对统治地位，但民航快递、中铁快运这具有强大行业支持的竞争者抢走了一大块与其相关的行业速递市场。而且正在逐步加大向深度、广度的渗透力度，对邮政速度逐渐形成威胁。面对竞争，邮政速递适宜采取的策略是( )。

A．市场开发

B．市场渗透

C．多角化经营

D．产品开发