单选题 Direct-mail advertising ______.

A、 uses letters as a chief means of providing information
B、 sends old customers detailed information about new products
C、 uses letters to tell prospective buyers about the local sellers
D、 sends over the prospective buyers sample products by parcels

【正确答案】 D

【答案解析】A、B、C项在文中均未提出，D项在第四段中有相关文字说明，选D。