What is the primary function of Yelp?

The primary function of Yelp is to serve as a platform for posting reviews about local businesses. Users can share their experiences, rate services, and provide feedback on a wide range of establishments, including restaurants, shops, and service providers. This user-generated content helps potential customers make informed decisions based on the real experiences of others. Yelp has become a significant resource for consumers looking to find and learn more about businesses in their area.

The other potential answers represent different kinds of platforms or tools that do not align with Yelp's main purpose. While booking reservations is a feature some businesses on Yelp may offer links to, it is not the essential function of the site. Sharing travel itineraries does not fit within Yelp’s focus on local business reviews, and a job search engine for the hospitality industry addresses a different need entirely, separate from what Yelp provides to its users. Therefore, the emphasis on user reviews and local business engagement makes option B the most accurate description of Yelp's primary function.