Mauricio Iragorri fell to his death down an empty elevator shaft after a repair person employed by International Elevator, Inc. (International) propped open the elevator door with a screwdriver and left the entranceway unattended and unbarricaded while the elevator car was not in place. Iragorri’s surviving spouse sued Otis Elevator Company. 

Her complaint alleges that International (the company that maintained and repaired the elevator in question) and OTESA (the company that installed the elevator in question) were negligent in their duties, and that the negligence of International and OTESA is attributable to Otis Elevator on a principal–agent theory. Explain what must be shown for the court to rule that International and OTESA were agents of Otis.