Which of the following is an example of public relations activity?

Hosting a media event to announce a new product is a prime example of a public relations activity because it involves engaging with the media and the public to build awareness and create a positive image for the product and the organization. Public relations focuses on fostering relationships and communicating with various stakeholders, including the media, to shape public perception. By organizing a media event, the organization creates an opportunity for journalists and influencers to learn about the product firsthand, ask questions, and share their experiences with their audiences, thus serving the broader goal of enhancing the brand's visibility and reputation.

In contrast, placing ads in magazines is primarily an advertising function aimed at promoting products or services through paid placements, rather than building communication relationships. Sending invoices to clients pertains to the administrative side of business operations, focusing on financial transactions rather than public engagement. Conducting market sales promotions is more aligned with sales strategy aimed at increasing immediate sales rather than managing public perception or relationships, which is at the core of public relations. Therefore, the hosting of a media event distinctly embodies the essence of public relations activities.