Concept: Acceptance is the final assent given by the offeree to the proposal. A valid acceptance converts a proposal into a promise.
Step 1: Check absolute and unqualified acceptance.
Acceptance must be absolute and unqualified. If acceptance contains conditions, it becomes a counter-offer.
\[
\text{Conditional acceptance} \neq \text{Valid acceptance}
\]
Step 2: Check prescribed manner.
If the proposer prescribes a particular manner of acceptance, acceptance should generally be made in that manner.
Step 3: Check subsisting offer.
Acceptance must be made while the offer is still alive. If the offer has lapsed or has been revoked, there can be no valid acceptance.
Step 4: Identify the incorrect statement.
Acceptance need not always be in writing. It may be oral, written, or sometimes inferred from conduct, depending upon the circumstances.
Therefore, the incorrect statement is that acceptance should in all cases be in writing.