Smiling Cow Dairy can sell all the milk it wants for $5 a gallon, and it can rent all the robots it wants to milk the cows at a capital rental price of $200 a day. It faces the following production schedule: Number of Robots Total Product (Gallons) 0 0 1 60 2 100 3 135 4 155 5 170 6 180 In what kind of market structure does the firm sell its output