4. Suppose that the marginal cost of producing a pound of cereal is $2, irrespective of the level of output, but there are also some fixed costs of production. Which of the following statements is correct? Select one answer a. The total cost curve is an upward-sloping straight line through the origin. b. The average cost curve is U-shaped. c. The marginal cost curve is a horizontal straight line. d. The marginal cost curve intersects the average cost curve at its minimum point