Darius Is a Purchasing Manager for a Large Auto Manufacturer

Darius is a purchasing manager for a large auto manufacturer. The contract with the company's steel provider is just about to expire, so Darius is negotiating the terms and condition of a new contract with his supplier. Darius is satisfied with the negotiations, so he takes the next step of drawing up a legal obligation to buy the negotiated amount of steel at the price and delivery date agreed upon by himself and his supplier. This legal obligation is otherwise known as

A) the cost of goods sold.
B) an agreement.
C) a bill of sale.
D) a purchase order.
E) a contract amendment.