Ancient remains are making the normally flat land hilly. What kind of complement is indicated by hilly?

predicate adjective, direct object, object complement, or predicate nominative

The correct answer for this question would be the third option: Object Complement. The kind of complement that is indicated by the word "hilly" is an object complement. The object of the sentence is "land". Object complement is a noun or an adjective which follows the direct object renaming or modifying it. Hope this answers the question.