If Annie Promises Not to Drink Alcohol Until She Is

If Annie promises not to drink alcohol until she is 21 years of age in exchange for her aunt's promise of $1,000,the agreement is:

A) enforceable because Annie is giving up the right to do something she would otherwise be entitled to do.
B) enforceable because both parties made a valid promise.
C) not enforceable because Annie does not have a legal right to drink alcohol.
D) not enforceable because Annie's aunt doesn't receive anything of value in exchange for her own promise.