Final answer:
The Doctrine of Respondeat Superior is most likely used to hold Milwall Inc. liable for the injury caused to the pedestrian by the accident.
Step-by-step explanation:
The doctrine that is most likely used to hold Milwall Inc. liable in this scenario is the Doctrine of Respondeat Superior. This doctrine holds that an employer is responsible for the actions of their employees that occur within the scope of their employment. In this case, Ryan was driving one of Milwall Inc.'s cars during company business when the accident occurred, making Milwall Inc. liable for the injury caused to the pedestrian.