How do the roles of AVC and ATC differ in the formation of the supply curve in the short run and long run?

• A. In the short run, the supply curve is the portion of the marginal cost curve above AVC, while in the long run, it is above ATC.
• B. In the short run, the supply curve is above ATC, while in the long run, it is above AVC.
• C. In both the short run and long run, the supply curve is the entire marginal cost curve.
• D. In both the short run and long run, the supply curve is the portion of the marginal cost curve below AVC.

Answer: (A)