Two Friends,Ann and Mary,are Having Margaritas at Happy Hour

Two friends,Ann and Mary,are having Margaritas at happy hour.There had been no discussion of who would pay for the drinks.After the third round of drinks,Ann said,"I will pay for everything tonight including your drinks." A couple of minutes later before any more drinks were ordered,Ann says,"I've changed my mind.I just remembered that they might be having layoffs at my toxic job tomorrow." Mary wants to force Ann to perform on her promise and threatens to sue.In this circumstance a court would:

A) not require Ann to follow through on the promise because it was a gratuitous promise.
B) require Ann to follow through on the promise under the doctrine of promissory estoppel.
C) require Ann to follow through on the promise if Mary had previously paid a comparable amount for food or drinks consumed by Ann.
D) require Ann to follow through on the promise if it would be a hardship for Mary to pay for her own drinks.
E) not require Ann to follow through on the promise because it would encourage Mary to drink.