Both Firm a and Firm B Emit 300 Tonnes of Pollution

Both firm A and firm B emit 300 tonnes of pollution. Suppose both firm A and firm B have permits that allow each to emit 100 tonnes of pollution. If it costs $5,000 for firm A to eliminate 100 tonnes of pollution and it costs firm B $6,000 to eliminate 100 tonnes of pollution, then

A) firm B will sell its permits to firm A for a price below $6,000.
B) firm A will sell its permits to firm B for a price above $6,000.
C) firm B will sell its permits to firm A for a price above $6,000.
D) firm A will sell its permits to firm B for a price below $6,000.