At any time after the grant of patent but before the expiry of a period of one year from the date of publication of grant of a patent,any person interested may give notice of opposition to the Controller in the prescribed manner on any of the following grounds,namely: (a) that the patentee or the person under or through whom he claims,wrongfully obtained the invention or any part thereof from him or from a person under or through whom he claims; (b) that the invention so far as claimed in any claim of the complete specification has been published before the priority date of the claim- (c) that the invention so far as claimed in any claim of the complete specification is claimed in a claim of a complete specification published on or after the priority date of the claim of the patentee and filed in pursuance of an application for a patent in India,being a claim of which the priority date is earlier than that of the claim of the patentee; Explanation.-For the purposes of this clause,an invention relating to a process for which a patent is granted shall be deemed to have been publicly known or publicly used in India before the priority date of the claim if a product made by that process had already been imported into India before that date except where such importation has been for the purpose of reasonable trial or experiment only