Which of the following is NOT an acceptable form of delivery for offer acceptance?

In contract law, the method of communicating acceptance of an offer is critical to ensuring that both parties have a clear mutual understanding of the agreement. Email, fax, and regular mail are all commonly recognized and acceptable forms of delivery for offer acceptance as they provide a written record of communication, which is essential in legal contexts.

When an acceptance is communicated via these methods, it typically fulfills the requirement of providing notice to the offeror that the offeree agrees to the terms of the offer. On the other hand, a phone call, while immediate and direct, does not offer the same level of documentation and can lead to misunderstandings about the terms accepted, as it does not create a traceable, verifiable record of the acceptance.

For these reasons, while a phone call may be a quick way to convey acceptance, it lacks the formal documentation that email, fax, and mail provide, making it less suitable as a definitive method of offer acceptance in a contractual context.