Disregard the Xs, kindly give explanation per answer

28. In a short-run production function of a perfectly competitive A. Constant firm, we expect average cost and average variable cost to be at a point where marginal cost is B. Increasing greater than average cost. X C. Decreasing D. Zero 29. Which of the following costs continuously decrease as a X A. Short-run average total cost firm's output increases? B. Long-run average total cost C. Average variable cost D. Average fixed cost 30. As opposed to a perfectly competitive industry, a profit- X A. lower; higher maximizing monopoly with identical costs of production will produce output and charge a B. higher; lower price. C. lower; lower D. higher; higher