إِنَّهُمْ مُغْرَقُونَ
Indeed, they are to be drowned.
This is the continuation of Hūd 11:37, strengthened with inna. The earlier prohibition against speaking for the wrongdoers makes their fate an anticipated topic. Thus the following report can be presented as answering a question that was never actually uttered.
Important distinction: The emphatic particle does not prove that Nūḥ denied the report. This example concerns the non-questioner being treated as a questioner, not the separate case of an actual denier.