A seller is considering extending trade credit to an existing customer that buys on cash terms. The customer has just placed a sales order (cash terms) for immediate delivery of 400 units at a sales price per unit of $100. The customer states that they will increase their sales order by 10 units if they receive a 90-day credit period. Variable costs are $65 per unit and involve an immediate cash outflow. The seller has an annual opportunity cost rate of 7.3%. At what sales quantity will the seller break-even (from an NPV perspective) by extending credit to the customer?

Select one:

a. 21 units

b. 400 units

c. 421 units

d. 450