Ralph Agrees to Lease an Apartment from Susan for One

Multiple Choice

Ralph agrees to lease an apartment from Susan for one day to see Thomas, the president of the United States, deliver a speech in the street below. The speech is canceled three days before its scheduled date. The contract is

A) ​discharged.
B) ​not affected in terms of Ralph's obligation to pay Susan.
C) ​postponed until another event is scheduled.
D) ​breached.