If Demand in the United States Is Given by Q₁

if demand in the United States is given by Q₁ = 13,200 - 600p₁, where p₁ is the price in the United States, and if the demand in England is given by 9,000 - 500p₂, where p₂ is the price in England, then the difference between the price charged in England and the price charged in the United States will be

A) $4.
B) $2.
C) $0.
D) $12.
E) $6.