Marginal Cost of Bikes A graph titled Marginal Cost of Bikes has the bike number of the x-axis, from 1 to 7, and marginal cost on the y-axis, from 0 to 70 in increments of 10. Bike 1 is 30 dollars, bike 2 is 18 dollars, bike 3 is 12 dollars, bike 4 is 20 dollars, bike 5 is 30 dollars, bike 6 is 50 dollars, and bike 7 is 60 dollars. A horizontal line is drawn at 50 dollars to indicate the market price. This graph shows the marginal costs of each bike, along with the market price. Select the correct answer from the options available. Based on this graph, at which level of production does the producer’s profit stop increasing? bike 4 bike 5 bike 6 bike 7