Which of the following provides that an acceptance is valid when it is placed in the mailbox?

A) The substantial performance doctrine.
B) The contract integrity rule.
C) The mirror-image rule.
D) The mailbox rule.
E) The contract legality rule.

Mailbox Rule

A legal principle stating that an offer is considered accepted once the acceptance is dispatched, not when it is received by the offeror.

Acceptance

In contract law, it refers to the act of agreeing to the terms of an offer, thereby creating a binding contract.