Carol says, "Pam, you're my best friend in the world. I just inherited a million bucks, and I want you to have some of it$.$ Come with me to the bank tomorrow, and I'll give you $$10,000."$ "Sweet!" Pam replies. Later that day, Carol has a change of heart. She is allowed to do so$.$ Examine the list of the elements of a contract, and cite the correct reason.