Final answer:
The market for milk is close to a perfectly competitive market due to many producers selling a similar product. Etsy represents a monopolistically competitive market with many unique products, while the market for plane tickets is an oligopoly with few dominating airlines. A rock concert ticket market is less competitive, resembling a monopolistic or monopoly market.
Step-by-step explanation:
When considering which of the following markets can generally be considered to be competitive, we need to think about market structures like perfect competition, monopolistic competition, and oligopoly. Markets that are perfectly competitive have many sellers offering identical products, making them price takers.
Agricultural markets, like the market for milk (option a), can often be considered close to perfectly competitive as they involve many producers selling a very similar commodity.
Contrastingly, Etsy (option b) is a platform with many unique handmade products, representing a monopolistically competitive market where products are differentiated and firms have some pricing power. The market for plane tickets from London to Tokyo (option c) would likely represent an oligopoly, as it is dominated by a few airlines with limited competition and high barriers to entry.
Finally, tickets to a particular rock concert (option d) would typically be a unique product with limited availability, making it an example of a monopolistic or perhaps even a monopoly market, depending on the exclusivity of the venue and the artist.