Discuss one of the following questions using information you have gained:

a. Can the parties agree in a contract for the purchase and sale of rice that the price for the rice will be the market value of rice on the day of delivery? Is this different from negotiations over the purchase and sale of a residence?

b. Are there situations when someone can be bound to keep their promise to take less for their goods than originally agreed, even though they received nothing in return for their promise? Is this different from negotiations over the purchase and sale of a residence?

c. If the parties sign a purchase and sale agreement for the purchase of an airplane and the airplane is destroyed shortly before the title to the airplane is signed by the seller, who bears the risk of loss?