Section 9(5)(i) in The Requisitioning and Acquisition of Immovable Property Rules, 1953
(i)Every person interested to whom an offer is made under sub-rule (3) shall, within fifteen days of the receipt of the offer, communicate in writing to the competent authority his acceptance or otherwise of the offer. If he accepts the offer, the competent authority shall enter into an agreement with him on behalf of the Central Government in Form "K".