Sanford and Son sells athletic equipment. The following events, related to a special customer order, occur as described below:

• September 1, 2019: Sanford receives the special order for 300 football helmets at a selling price of $100 each, including delivery at a future convenient time and location. The customer, with whom Sanford has had a long-term, trouble-free relationship, pays $5,000 as a deposit, and agrees to pay the rest on delivery. Sanford immediately orders $20,000 worth of helmets from its supplier and pays a $5,000 deposit for them.
• September 20, 2019: Sanford pays a $15,000 balance due to the supplier upon delivery of the helmets to its warehouse.
• October 1, 2019: The customer calls for delivery of the helmets and pays the balance of $25,000 when they arrive at the customer site.

What is the gross margin that Sanford earned on the order?

a.) $10,000

b.) $20,000

c.) $25,000

d.) $30,000