Answer:
The answer to the question: If Stan is liable for this accident, what is the source of his liability?, would be, B: Vicarious liability.
Step-by-step explanation:
Although Stan was not directly responsible for Martha´s accident, nor for Mason´s negligence, he is still liable as Mason was under his employment, and the accident happened during Mason´s working hours. Under the law, vicarious liability will always affect the employer as they are considered responsible for ensuring that the employee correctly performs the tasks under his job description and to the best of their ability. This also includes an employers responsibility to supervise the worker. Therefore, because the accident happened under Stan´s employment, in Stan´s apartment building, and during normal working hours for Mason, Stan is also liable, and this liability is called vicarious liability.