Answer:
C. supply and demand predicts that the price will rise by $2 to eliminate the shortage
Explanation:
If there is currently a shortage of 20 units of the good, then the law of supply and demand predicts that the price will rise by $2 to eliminate the shortage.
Shortage leads to lesser supply of the good and demand being same the so, by the law of supply and demand the price of the goods will rise by some amount in order to compensate the shortage.