advertisement uses words and pictures the advertisers think of to convince people to buy

问题补充：

advertisement uses words and pictures the advertisers think of to convince people to buy product or service, or to believe in an idea.

A. An; the; a; /

B. An; /; the; a

C. The; /; a; /

D. The; the; /; the

答案：

(答案→)A. An; the; a; /

B. An; /; the; a

C. The; /; a; /

D. The; the; /; the

解析：考查冠词。句中an advertisement泛指广告；the words and pictures特指广告中所用的文字和图片；a product一件产品；service服务，为不可数名词，故选A。