Answer: The correct answer is "A. bilateral.".
Explanation: Windsor, the owner of Windsor's Sandwiches, contacts Gary, a new supplier. He promises Gary that he will pay him $375 if Gary delivers 20 pounds of cheese the following morning. Gary promises to make the delivery as requested by Windsor. This creates a BILATERAL contract between them.
It is a bilateral contract because it produces effects and obligations for both parties, Gary is obliged to deliver 20 pounds of cheese the next morning and the owner of Windsor is obliged to pay Gary $ 375 for it.