Indian Contract Act, 1872
7. Acceptance must be absolute
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.