The best example of a firm operating in a monopolistically competitive market is: C. a family restaurant.
A monopolistically competitive market can be defined as the market that tend to sell similar product but in which the product of some of them are slightly differentiated and this companies compete against each others.
Restaurants tend to operate in a monopolistically competitive market based on the fact that there are many restaurants that sell similar products but in which one of the restaurant are a little differentiated from those of other restaurants.
Therefore the correct option is C.
Learn more about monopolistically competitive market here:https://brainly.com/question/25717627
#SPJ1