Economic theory predicted that the price of a depletable resource would rise by 10 percent. In reality, the price fell by 5 percent. Which of the following events could explain this discrepancy?

a.Antitrust enforcement broke up a cartel among major suppliers of the resource.

b.Known reserves of the resource were depleted.

c.The government imposed an effective price floor.

d.The interest rate rose by 15 percent.