Recruiting the right candidate to fill a vacancy can be a difficult and costly task. Appointing the wrong person could be an expensive mistake which could cause personnel problems for the whole department. And, as every HR manager knows, it is much more difficult to get rid of someone than it is to employ them. The HR managers first decision is whether to recruit internal applicants or advertise the vacancy outside the company. Internal applicants are easy to recruit by memo, e-mail or newsletter. Further more, they are easy to assess and know the company well. However, they rarely bring fresh ideas to a position. Moreover, a rejected internal candidate might become unhappy and leave the company. Recruiting outside the company means either advertising the vacancy directly or using an employment agency. If the company decides to advertise the vacancy directly, it has to decide where to place the advertisement. Traditionally this has meant newspapers and professional journals but now the Internet is also very popular. The decision normally depends on the vacancy. Companies advertise blue-collar or clerical jobs in local newspapers and senior management positions in national papers or professional journals, while the Internet is one of the best ways of advertising IT vacancies or recruiting abroad. However, with the Internet there is a risk of receiving unsuitable applications from all over the world. An agency can he either a commercial business or a government employment center, A company often uses a government agency to recruit blue-collar workers but normally prefers a commercial agency for its white-collar staff. However, a commercial agency could be very expensive and the applicants are less likely to stay with the company for a long time.
The central idea of the first paragraph is that______.

A. finding the right job applicant to fill a vacancy is never easy
B. removing an undesirable employer is more difficult than hiring him
C. personal problems can come up if the manager employs a wrong candidate
D. every HR manager knows the troubles and expenses of recruitment