1. When the marginal product of labor increases, does the marginal cost of output rise or fall? Explain. 2. Once diminishing marginal returns take hold, does the marginal cost of output rise or fall? Explain. 3. Is the total cost curve inversely related or directly related to the variable cost curve? Explain. 4. Are the average cost curves able to keep falling beyond their point of intersection with the marginal cost curve? Explain