Advertising is a highly developed twentieth-century industry. The development of radio, television, cinema, magazines and newspapers has gone _ with the development of advertising. Why is advertising so popular? Is it a waste of money? It has been proved again and again that repeated advertising increases product sales. Since it increases production, the price can be reduced. Therefore advertising, instead of making a product more expensive, makes it cheaper. Advertising is now a scientific business. Once managers would say jokingly, " I know that half of what I spend on advertising is wasted, but I don't know which half." Now, all parts of an advertising program are properly measured and researched. What makes a good advertisement? There have been major changes in advertising in the past sixty years. People read advertisements partly for information and partly for pleasure. Today's advertisements often start with a question, or a puzzle, with the purpose of attracting the reader's attention. Of course, most advertisements contain information. But this is usually contained in a text that is interesting and often funny. Humor is very important. Sometimes advertisements tell a story, or the story may be continued over a number of advertisements. However, there is a danger in this. It is possible that the reader or viewer will remember the advertisement but not the name of the product. The purpose of advertising is   _  .
to increase product sales to make a product much better to spend more money to reduce the production