Which scenarios are enforceable bargains?

A) Caroline tells her sister Jean that if Jean will run Caroline's business for a month while Caroline is away on vacation, Caroline will make the down payment on a new car for Jean. Jean has wanted a new car ever since she got her Driver's License.

B) Mickey promises his son Michael, while he is dropping him off at his first day of college, that Mickey will give him $200 of spending money every month.

C) A grandfather tells his granddaughter that if she quits her job, he will provide her with an income.

D) Elsa promises her nephew Edgar that if he leaves his job to go back to business school, she will pay his expenses for the two years he is in school, as long as he chooses to attend a school in Boston, where Elsa lives, and agrees to visit Elsa once a week.