In Which of the Following Cases Can We Be Certain

Multiple Choice

In which of the following cases can we be certain that a natural resource has become scarcer?

A) both the demand for the resource and the supply of the resource have increased
B) both the demand for the resource and the supply of the resource have decreased
C) demand for the resource is unchanged and the supply of the resource has increased
D) the demand for the resource has decreased and the supply of the resource is unchanged