Which of the following relationships between short-run curves holds most accurately?

a. The short-run AVC exceeds the short-run ATC at any given level of output.

b. If the short-run ATC curve is rising, the short-run AVC curve is declining.

c. The short-run AFC is always falling with increased output, whether the short-run MC curve is greater or less than short-run AFC.

d. If short- run MC is less than short-run AVC, short-run AVC is rising.