Which of the Following Will Be Legally Binding on All

Which of the following will be legally binding on all the parties despite the lack of consideration?

A) A promise to donate money to a charity which was relied upon by the charity in incurring large expenditures.
B) An oral employment agreement for a term of nine months from the date the agreement was formed.
C) An irrevocable oral promise by a merchant to keep its offer open for 60 days.
D) A material modification signed by the parties to a contract to purchase and sell a parcel of land.