[不定项选择题]资料：Above the line promotion uses mass media such as the press,radio,television,cinema or poster sites. This type of promotion is usually paid for. Each of the possible media methods can be used to target audiences in different market segment. There are both strengths and drawbacks to these forms of media: UNISON embarked on a wave of television, internet and newspaper adverts for the million voices campaign. They wanted that the vital services provided by public sector workers could disappear if the funding cuts sent ahead. The adverts featured a lot of vital public service jobs fading out of sight and featured the tagline. Don't wait until they're gone to defend them. A powerful campaign film was also released that illustrated how local communities would be affected by cuts. A version of this film aimed at recruiting members to UNISON was shown on television using DRTV. The online and newspaper adverts linked back to the campaign website where people can register their support and add a comment. Which of the following is not true about these forms of media?
A.it is hard to evaluate the effectiveness of a campaign.
B.the media are often expensive.
C.it aims at specific audiences.
D.it may have an immediate impact.