ProGo plans to sell 1,200 carriers next year and has budgeted sales of $48,000 and profits of $20,000. Variable costs are projected to be $22 per unit. Nathan Co. offers to pay $21,000 to buy 600 units from ProGo. Total fixed costs are $5,000 per year. This offer does not affect ProGo's other planned operations. The incremental revenues for this situation are:
a) $21,000.
b) $7,800.
c) $27,000.
d) $6,000.