The law of diminishing marginal returns
a. explains why the average total cost and marginal cost curves are uminusshaped in the short run.
b. causes average total costs to rise at a decreasing rate as output increases.
c. explains why the average total cost, average fixed cost, and the marginal cost curves are uminusshaped in the short run.
d. causes the difference between average total cost and average variable cost to get smaller as output increases.]
