The correct answer is: A. the communication of notice of revocation by the proposer to the other party.
A proposal can be revoked at any time before acceptance, unless it is made irrevocable by the offeror:
- by stating that it is irrevocable, or
- by the conduct of the parties which shows that they intend it to be irrevocable, or
- where it is part of a contract made by deed.
Once a proposal has been accepted, it cannot be revoked.
Option B is incorrect because the failure of the acceptor to fulfil a condition precedent to acceptance does not revoke the proposal. A condition precedent is a condition that must be fulfilled before the contract becomes binding. If the condition is not fulfilled, the contract does not come into existence and the proposer is not bound by it.
Option C is incorrect because the lapse of the time prescribed in such proposal for its acceptance does not revoke the proposal. The proposer can still accept the proposal after the time has lapsed, but the acceptor may be able to claim damages for late acceptance.
Option D is incorrect because an act involving moral turpitude of the proposer, whether related to the proposal or otherwise, does not revoke the proposal. Moral turpitude is a term used to describe conduct that is considered to be morally wrong. If the proposer commits an act of moral turpitude, it may affect their reputation and make it difficult for them to enter into contracts in the future, but it does not revoke a proposal that has already been made.