A person interested in the fire protection district, or in a local improvement district therein, involved in the petition or in any proceedings sought by the petition to be examined, approved, and confirmed by the court, may answer the petition. The statutes of this state respecting answers to verified complaints are applicable to answers to the petition. The person so answering the petition shall be the defendant in the special proceeding, and the board of fire commissioners shall be the plaintiff. Every material statement of the petition not specifically controverted by the answer must, for purposes of the special proceedings, be taken as true, and each person failing to answer the petition is deemed to admit as true all the material statements of the petition.