A wheat farm is most likely to operate within a market structure of PERFECT COMPETITION.
In a perfectly competitive market, there are many buyers and sellers, the products are homogeneous (identical), and no single buyer or seller can influence the market price. Wheat farming fits this description as there are many wheat farmers producing a similar product, making individual farms unable to affect the market price of wheat significantly.
In contrast, a shoe company, an automobile manufacturer, and an office supply store typically operate in more monopolistic or oligopolistic markets with differentiated products, branding, and the ability to influence prices.