Which of the following is not held constant in a demand schedule?

Refer to Figure 13-13. If the diagram represents a typical firm in the market, what is likely to happen in the long run?

A) Inefficient firms will exit the market and new cost-efficient firms will enter the market. B) New firms will enter the market causing the demand to decrease for existing firms. C) Competition will be intensified as firms strive to make long-run profits. D) Some firms will exit the market causing the demand to increase for firms remaining in the market.

When a tax is placed on the sellers of cell phones, the size of the cell phone market

a. and the effective price received by sellers both increase. b. increases, but the effective price received by sellers decreases. c. decreases, but the effective price received by sellers increases. d. and the effective price received by sellers both decrease.