Mary Invites Some Friends to Dinner, and They Accept

Mary invites some friends to dinner, and they accept. They purchase a much more expensive bottle of wine than they would normally drink and a beautiful bouquet of flowers. Mary calls them two hours before the dinner to tell them she has been invited out by the man of her dreams and is postponing the dinner.

A) The friends can claim the cost of the flowers and the wine since Mary has breached the contract.
B) Since Mary is merely postponing the dinner, she has not breached their dinner contract.
C) Even though they accepted her dinner offer, this is not a situation in which one party can sue another, since no reasonable person would think that there was any intention on Mary's part to create a legally enforceable contract.
D) Mary may not have intended to be bound to her promise, but her friends have suffered a loss and she cannot now claim she did not mean to enter a contract to provide dinner since she did not say that when she made her offer.
E) No agreement between friends can be enforced as a contract, including this one.