Final answer:
Sales promotion agencies, digital/interactive agencies, and public relations firms are participants in the advertising and promotions process.
Step-by-step explanation:
The major participants in the advertising and promotions process include advertising agencies, media organizations, collateral service agencies, specialized marketing communications service agencies, and public relations firms. Sales promotion agencies, digital/interactive agencies, and public relations firms fall under the category of specialized marketing communications service agencies.
They play a crucial role in planning and executing marketing campaigns, creating promotional materials, managing public relations, and implementing sales promotion strategies.