Many residents of Calovia are committed to using products containing recycled materials.  Soon these consumers will get help in identifying such products from a book being published by the Calovian government.  The book offers a comprehensive listing, by product type and brand, of goods sold in Calovia that contain recycled material.  Therefore, publication of the book will almost certainly increase the use of products containing recycled materials in Calovia.

Which of the following, if true, most strengthens the argument?

1. Proceeds from the sale of the book are not expected to exceed the cost of its publication.
2. For numerous types of products, there are many brands that use recycled materials, although their manufacturers and distributors do nothing to advertise those brands’ recycled content.
3. For many materials, such as plastics, the recycling process results in a lower grade of material with a correspondingly different range of uses.
4. For many types of products listed in the book, all the brands available in Calovia use recycled materials.
5. Many manufacturers of products that contain recycled materials vary the proportion of recycled materials in those products in response to changes in price and availability.

答案是B,但我选了D.请帮忙解释.

题目说C地区很多人用含回收物质的产品。 C政府要发行一本书， 包括所有在C地区买的含回收物质的产品的牌子等信息。 这本书会提高含回收物质的使用。问strengthen

B说，对于很多类产品， 很多牌子用了回收物质， 但是这些厂商并没有在这方面做广告－》 有了这本书。 买这些类产品的消费这就会买书上列的那些牌子 －》 提高含回收物质的使用。

D说， 对很多类产品， 所有的牌子都用回收物质。 －》 没这本书， 大家买的也还是含回收物质的产品 －》 没影响。