Almost every holiday season at least one gift idea achieves fad status. When that happens, prices tend to increase dramatically. Why?

A.The demand curve for fad items is upward-sloping.

B.Quantity demanded exceeds quantity supplied.

C.Too much government regulation in the market.

D.Sellers want to take advantage of people who received a year-end bonus.

正确答案：Quantity demanded exceeds quantity supplied.