Here is the question in the textbook. The answer given to this problem on coursehero is wrong because the gift card is not given in exchange for the car, but is given as consideration for the option contract. However, it is "past consideration," thus not enforceable unless it is considered as Promissory Restitution. Can someone please explain an in depth answer to this question? Thank you!

"Calvin wanted to sell an old car he had inherited from his aunta Morris Oxford, which is an obscure British car manufactured in the first half of the twentieth century. Calvin was not a collector of old cars, so he had an expert estimate the fair market value, which was determined to be $10,000. Calvin put messages on various websites that specialized in British cars stating that he wanted to sell the car for $10,000 and giving the details of the car. Victor is an avid collector of British cars, especially the Morris; however, Victor did not have the $10,000 needed to purchase Calvin's car. Victor emailed Calvin asking if Calvin would hold the car while Victor tried to raise the $10,000. Calvin replied in a signed email, "Victor, yes. You may purchase my Morris Oxford car for $10,000. I promise to keep this offer open for ten days and not sell to anyone else." Victor was so delighted that he immediately replied, "Thank you so much. In return for your option, I want to give you a $5 gift certificate for groceries, which can be redeemed at any major supermarket." In his email, Victor included a link to the gift certificate, which he had purchased online.p. 246 If Calvin sells the car to another party before the ten days pass, will Victor be successful in a breach of contract action, asserting that Calvin's offer was irrevocable? Explain your reasoning."