How proposal may be revoked

A proposal is revoked: 1. By the communication of notice of revocation by the proposer to the other party in the manner prescribed by sections 9-03-17 and 9-03-19 before the latter's acceptance has been communicated to the former; 2. By the lapse of the time prescribed in such proposal for its acceptance, or if no time is so prescribed, the lapse of a reasonable time without communication of the acceptance; 3. By the failure of the acceptor to fulfill a condition precedent to acceptance; or 4. By the death or insanity of the proposer before acceptance of the proposal.