Three promotional materials used by public relations include:
laws
pamphlets
books
articles

Pamphlet

Books

Article

Explanation: The three promotional materials used by public relations include pamphlets, books, and Article. however, several organizations also use public relations to promote their products and to supplement their sales efforts. Public relations can help to improve and promote an organization’s image and products by creating a positive awareness of new products and the organization producing it. Public relation helps promote positive attitudes and behaviours towards your business that will help convert interested consumers into actual customers.

b: the establishment clause  

b: socialism