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.

为什么答案选B