What is the key factor in determining whether Buy-Mart is liable under this doctrine? 

Lynne Meyer, on her way to a business meeting and in a hurry, stopped at a Buy-Mart store for a new pair of nylons to wear to the meeting. There was a long line at one of the checkout counters, but a cashier, Valerie Watts, opened another counter and began loading the cash drawer. Meyer told Watts that she was in a hurry and asked Watts to work faster. Instead, Watts only slowed her pace. At this point, Meyer hit Watts. It is not clear from the record whether Meyer hit Watts intentionally or, in an attempt to retrieve the nylons, hit her inadvertently. In response, Watts grabbed Meyer by the hair and hit her repeatedly in the back of the head, while Meyer screamed for help. Management personnel separated the two women and questioned them about the incident. Watts was immediately fired for violating the store’s no-fighting policy. Meyer subsequently sued Buy-Mart, alleging that the store was liable for the tort (assault and battery) committed by its employee. Using the information presented in the chapter, answer the above question.