Answer: Opinion leaders
Explanation: Opinion leaders, or as they are called, influencers, are in fact experts within a particular branch or industry. They are the ones who make the decisions that are important for the business of the industry or in this case the restaurant, and their opinions and merits are believed, as they have proven through their earlier decisions and influence. That's why they used to be called industry insiders or decision makers.
Not only is their influence known in a narrow circle of people of a particular branch or industry, but this influence is widely known and certainly influences and shapes public opinion. Therefore, if someone, like this winery, wants to sell wine, then it is a good idea to present it in restaurants with chefs who are already well known, i.e opinion leaders, because restaurant guests and other customers will definitely trust them. So the mere fact that a famous chef works in a restaurant where the wine is sold is reason enough to buy the wine.