The Economy Was at Point a Producing 100X and 200Y

Multiple Choice

The economy was at point A producing 100X and 200Y. It then moves to point B where it produces 200X and 300Y. It follows that

A) point A may have been a point below the economy's PPF, while point B may lie on the PPF.
B) the economy's PPF could have shifted inward and point A was a point on the economy's old PPF.
C) the economy has moved from one point on its PPF to another point on the same PPF.
D) the economy moved from an unattainable point to an attainable point.