The Following Graph Shows the Supply of and Demand for Baseballs

The following graph shows the supply of and demand for baseballs in the United States.If the world price is $3 per baseball and a tariff of $1 per baseball is imposed,then the number of baseballs purchased in the United States is _____.

A) 4,000
B) 6,000
C) 8,000
D) 10,000
E) 12,000