Advertising is a highly developed twentieth-century industry

Advertising is a highly developed twentieth-century industry.The development of radio,television,cinema,magazines and newspapers has gone hand in hand 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 programme are properly measured and researched.
What is meant by what managers said in the second paragraph?
A.All the money on advertising was wasted.
B.Not all the advertisements were well designed.
C.All the managers knew about advertising then.
D.Managers spent no money on advertising