Some people believe that you have to be a special kind of person to sell a product. But although it is clear that a successful salesman does need special talents and an open personality, many of the skills be uses are used by us all.We build and keep relationships with different kinds of people, we listen to and take note of what they tell us and don’t just enjoy the sound of our own voices, and we explain things to them or discuss ideas with them.In the same way, any company needs to establish a personal relationship with its major clients and potential customers. It is often said that "people do business with people": a firm doesn’t just deal impersonally (没有人情味地) with another firm. A person in the buying department regularly receives personal visits from people representing the firm’s suppliers (供应商)—or in the case of department stores or chain stores, a team of buyers may travel around visiting their suppliers.Keeping sales people "on the road" is much more expensive than employing them to work in the office, Much of the sales people’s time is spent unproductively traveling. Telephone selling may use this time more productively, but a face-to-face meeting and discussion is much more effective. Companies involved in the export trade often have a separate export sales force. Its travel and accommodation expenses may be very high. As a result, servicing overseas customers may often be done by phone, telex (电传)or letter, and personal visits may be less often. Many firms appoint an overseas agent or distributor (分销商) whose own sales force takes over responsibility for selling their products in another country The passage indicates that some companies use telephone selling because（）.

A. they have too many sales people
B. their sales people don’t like travelling
C. it saves time
D. it is more polite