Tammy was shopping in Save-a-Lot Grocery Store when Stewart, an employee, brushed Tammy’s ankle with a grocery cart. A short time later, while still shopping, Tammy told Stewart that he should say “Excuse me,” and then people would get out of his way. Stewart then punched Tammy in the face, knocking her to the floor. If Tammy sues Save-a-Lot, what legal issue must be addressed to determine whether Save-a-Lot is liable?