The correct answer is: D: them. Object in the sentence is the entity that is acted upon by the subject. In this sentence, subject is "he", and "he" is doing the action of locating upon "them". Types of object are: 1) direct object: entity acted upon. Example: Suzan is making a CAKE. 2) indirect object: entity indirectly affected by the action. Example: Tom sent HER flowers. 3) prepositional object: object introduced by a preposition (to, for) Example: Tom is waiting for GEORGE.
