Boris Agrees to Paint Andrew's House on the Third Week

Boris agrees to paint Andrew's house on the third week of April 'provided it doesn't rain'. In which of the following situations has the contract been breached?

A) Before performance, Boris is offered a more lucrative contract by Cynthia for the same period. Andrew and Boris agree to cancel their agreement.
B) Before performance, Andrew's house burns down.
C) On the third week of April, there is a torrential storm and it rains incessantly.
D) Just before the third week of April, the paint manufacturer sends Boris the wrong kind of paint and he can only start the work a week later than planned.