Concept:Marginal cost (
MC) is the additional cost of producing one more unit of output.
Explanation:In the short run, as output increases, marginal cost first falls due to increasing returns to the variable factor.
Later, after a certain output level, diminishing returns set in and marginal cost begins to rise.
So the usual shape of the marginal cost curve is U-shaped, falling initially and then rising.
It does not fall continuously, remain unchanged, or rise first and fall later.
Answer:B. falls and later rises.