Minn. Stat. § 508.17: ANSWER.

Any person claiming any right, title, estate, or interest in or lien upon the land, whether named in the summons or not, may file an answer therein, within the time named in the summons, or within such further time as may be allowed by the court. The answer shall state all objections to the application, set forth the right, title, estate, interest, or lien claimed by the party filing the same, and be signed and verified by the defendant, or by some person in the defendant's behalf.