【单选题】Suppose the United States government is successful in reducing the flow of drugs into the United States. What impact does this have on the supply and demand curves for illegal drugs.
A.
supply decreases, demand is unaffected, and price increases.
B.
demand decreases, supply is unaffected, and price decreases.
C.
demand and supply both decrease, leaving price essentially unchanged.
D.
supply decreases, demand increases, and price increases substantially.