Yet there is another important aspect of advertising that should not be forgotten: that of choice. A number of advertisements for different brands of the same product, e.g. toothpaste, shampoo or washing powder allow the consumer to choose. Choice is an important part of buying.
In this busy day and age, there is little time for comparison shopping. To determin which product is the best to buy, and at the most competitive price, consumers these days rely on advertising in its various forms. This saves time and energy and simplifies shopping. So for busy people like you and me, advertisements actually do us a favor.
What is the dual function of advertisements？

A. To sell and to inform.
B. To increase prices and competition.
C. To change the means of selling and buying.
D. To take away chances of choosing from customers.