A good advertisement people attach positive meanings can contribute to the sales of a p

问题补充：

A good advertisement, people attach positive meanings, can contribute to the sales of a product．

A. for which

B. to which

C. of which

D. on which

答案：

A. for which

(答案→)B. to which

C. of which

D. on which

解析：考查定语从句。attach to依附，附属,故用to which，选B。