Concept of buying an offer to be held open for a further decision. The option in the option contract does not have to be exercised. In a unilateral contract, beginning performance is an option contract under Restatement 45. Offeree can decide not to fully perform, but the offeror must leave the offer fully open. Myth of option contract exist as long as someone is performing.
Revocation is possible once performance has failed or terminated without being fully executed.
Patterson rule- unilateral offer can be revoked.