If spending decreased by $400, and the GDP decreased $1,000 as a result, the MPC must be:

Which of the following is true for a profit-maximizing competitive firm in the long run but not a monopolist?

a. MC = MR b. MC = P c. AR = P d. Q > 0

Ceteris paribus, which of the following is most likely to cause a decrease in the supply of skateboards?

A. An increase in the price of skateboards. B. An improvement in skateboard-making technology. C. An increase in the cost of materials used to produce skateboards. D. All of the choices are correct.