In order to convert a proposal into a promise, the acceptance
must—
(1) be absolute and unqualified;
(2) be expressed in some usual and reasonable manner, unless the proposal prescribes the manner
in which it is to be accepted. If the proposal prescribes a manner in which it is to be accepted, and the
acceptance is not made in such manner, the proposer may, within a reasonable time after the
acceptance is communicated to him, insist that his proposal shall be accepted in the prescribed
manner, and not otherwise; but if he fails to do so, he accepts the acceptance.